Richard Iverson Oral History Interview, December 1, 2017

SAMUEL SCHMIEDING: Good morning. It is December 1, 2017. This is Dr. Samuel J. Schmieding, Oregon State University College of Forestry here in the U.S. Forest Service's Forest Science Laboratory and we are here with Dr. Richard Iverson, Senior Research Hydrologist with the USGS. Been with the USGS 35 years and most of that time he's been stationed at the Cascades Volcano Observatory in Vancouver, Washington. Today we are going to do an oral history interview which is part of Group II of the H.J. Andrews Oral History Project which started back in 2013. We're going to talk about Dick's career in geology with a specific focus on the debris flow flume which was built at the H.J. Andrews Experimental Forest in the early 1990s, but we're not going to be limited to that subject. Anyway, good morning, Dick, how are you?

RICHARD IVERSON: Good morning. I'm just fine.

SS: I want to thank you for being willing to meet with me. These are always a 00:01:00process and they're interesting. I really appreciate it. Let's just start at the very beginning. Where were you born and raised, or just give me a little biographical sketch, however you want to.

RI: I was born in Southern Minnesota in a small town called Albert Lea, Minnesota. My parents were living on a farm at that time working as farmers. I spent most of my childhood, however, in Iowa. When I was too young to remember we moved from Minnesota to Iowa and I grew up in several different towns. The ones that I remember most distinctly were Denison, Iowa; Ames, Iowa; and Sioux City, Iowa. During that time, my father was working for the Iowa State University Extension Service and was changing jobs, sort of moving up the ladder of responsibility. That's why we shipped it from town to town.

SS: So, you understand Lake Wobegon humor, then, right?

RI: I absolutely understand Lake Wobegon humor. I understand a lot about how university politics work. Both my brother and sister are university professors.

SS: Really? In what field?

RI: Actually, my brother is also a geologist. His specialty is glaciology and he's at Iowa State University where both he and I were undergraduates many years ago. Then my sister, who's older than me, is a professor of landscape architecture at the University of Michigan.

SS: So, you're a Cyclone fan?

RI: I'm a Cyclone fan.

SS: They're pretty good this year in football.

RI: Kind of dyed in the wool. Once you're hooked as a kid that doesn't go away.

SS: They actually have a pretty good football team this year.

RI: They did pretty well.

SS: They even beat Oklahoma, if you can believe that.

RI: The only team to beat Oklahoma.

SS: Yeah, I know. I watched it.

RI: I unfortunately didn't see the game, but I heard about it.

SS: I was very pleased because I don't like Baker Mayfield. What was your childhood like, especially in relation to the natural world? You were in the Midwest in rolling hills, farm, flat country.

RI: Exactly.

SS: Tell me about that.

RI: I think largely because of my parents' interests and my dad in particular, I always had a real sense of connection to the outdoors and to the landscape and so forth. Spending time on a farm as a small child visiting my grandparents' farm was something that was special. Even more importantly for me, and I think what led me to become a geologist, was camping trips that we would take to the Rocky Mountain states, usually Wyoming or Colorado. I remember one camping trip in particular, because I think maybe I was old enough at that time to really appreciate things more than I had when I was younger. It was 1963 and we took a long camping trip to Grand Teton and Yellowstone National Parks, which at that time were a lot less crowded than they are nowadays. It was just so spectacular. 00:04:00I couldn't imagine anything better than seeing nature exposed in those ways and being most impressed of all just with the landscapes and thinking about how they had changed over time and what does it take to create this kind of spectacular scenery.

SS: How would you characterize the contrast between the Midwestern topography and ecology with the Rocky Mountains in terms of inspiring you to have a career or doing science and studying natural processes?

RI: The thing about the Midwest, at least the part of it that I grew up in, is that there's really remarkably little of it that's anything resembling a pristine state. The one exception to that might be along a river bottom. I did spend a lot of time as a kid playing around in creeks and fishing, and so forth and so I did get an exposure to nature in that sense.

Other than that, things are largely developed. Of course, mostly it's farmland. You see the landscape very clearly, but it's all covered with crops and largely surrounded by fences at that time, because in those days they would also turn cattle out in the fields after they were done harvesting. There was certainly a connection to nature, but seeing things in a more natural state as was true in the national forests and the national parks of the west-really, to me it was just a tremendous eye-opener to be exposed to that.

SS: You became a scientist later who would study disturbance processes and dynamics to some degree. What in the Midwest that maybe other type of disturbances on a very small scale maybe, or arroyo cutting or tornadoes, or anything that made you think shook you up in thinking about earth and processes 00:06:00in a real remedial, even pre-academic kind of way.

RI: I would say as a boy growing up in these Midwestern towns, again I spent a lot of time on, in, and around creeks, small streams, typically no more than 10 m wide. I was always really fascinated by just watching what was going on with the moving water and the movement of sediment and so forth. Of course, it was very conspicuous whenever there was a construction project or anything of that nature that was tampering with the creek that things changed dramatically.

SS: You could see the turbidity change and...

RI: You could see more erosion; you could see that the creek wasn't looking the way it used to look. I certainly didn't think about it in intellectual terms in those days. I was too young, I think, but I think it had a deep imprint on me 00:07:00just in terms of thinking about how nature works and how sediment moves and the role of water and so forth. I was always fascinated by that. I remember one experience in particular in a creek near our house where we had a particularly cold winter and the creek froze essentially solid from top to bottom. The ice was over a meter thick. In the process of freezing the ice had arched up in various places and there were actually tunnels you could get into by clamoring down the stream bank and you could get in underneath the ice and be crawling around basically on the stream bed. You would see frozen fish that were trapped in the ice. You could see all these things frozen in time, literally, and get some sense of what that stream bed was like, which you ordinarily of course could never get just from being there in the summertime. Because our streams in the Midwest were never clear mountain brooks. You basically couldn't see through 00:08:00the water. The water was pretty muddy most of the time.

SS: Well, and it was also slow moving.

RI: And slow moving.

SS: It had a high particulate and organic material content-

RI: Exactly.

SS: -built into the matrix of the water.

RI: Exactly.

SS: Now, taking off on that, and I'm thinking about mythologies and first impressions and how we first see things as a child and how they create a mythology and a perception. What are your early memories about geologic processes and disturbances in particular that you witnessed in person or saw in the media? I mean on news, books, films, art, that influenced how you viewed such processes as a child and did this create a stereotype that you had to overcome as an adult when you became an intellectual. I give you the example of myself when I first saw the first pictures of Hawaii volcanoes and the runny lava and also a Tarzan movie with this very weird stereotypical flow of lava in it from a '30s movie.

RI: Sure.

SS: That perception was in my head until I became an adult and studied it. Did you ever have something like that that was a perception and then you had to counter that and become an adult and an intellectual person?

RI: I can't think of anything that specific. Certainly, where I grew up in Iowa the most profound experiences that one had in terms of seeing very powerful natural processes at work were all related to weather events, whether it was tornadoes, powerful thunderstorms, hailstorms, we had a lot of strong wind, and so there was a great deal of exposure to just how unpredictable nature could be in terms of generating these kinds of weather events. I think the other thing in those days it's easy to forget now, but weather forecasting was much poorer then than it is now. They didn't have all the modern technology. As a consequence, there were a lot more surprises in the weather. Nowadays when tornado weather is 00:10:00forming in the Midwest, generally they can anticipate it a couple days in advance.

SS: And you turn on the weather channel.

RI: You turn on the weather channel and you track things and then you have all the radar images and everything. None of that was available then. It would just often take you by surprise. I remember times being out on just some of these little fishing excursions where just seemingly out of nowhere a huge storm would boil up and suddenly this small lake has huge waves on it and you're struggling to get back to shore on your tippy little boat and so forth. I think there was an imprinting at that time in terms of just nature in general and how unpredictable and sometimes violent it can be, and humans have to learn to adapt because we're not going to change this. This is just the way nature is. We have to be flexible and learn to adapt.

SS: Did you ever have any close calls with tornados?

RI: Not terribly close calls. There was one circumstance, well, two that stick in my mind. I remember once we were driving out on a country road and we saw a tornado approaching across the flat terrain probably a mile or two distant. Of course, with a tornado you never know exactly which way it's going to turn, but generally speaking you can outrun a tornado in a car as long as you're not trying to drive toward the tornado as some storm chasers do. It wasn't terribly scary, but it was impressive to see it standing out in bold relief against the backdrop of sky. There was another time when I was a bit older when a tornado did pass directly over our house. Luckily it did no damage to the house, but it did bring down a tremendous amount of wood out of the trees. I was a teenager at the time, and I spent a week, at least, cutting up wood and so forth, big branches, that have crashed down out of our trees.

SS: What was the first time you came to the northwest? Was that as an adult?

RI: Yeah, as a very young adult. I had never spent any time at all on the west coast prior to moving to California to attend graduate school at Stanford in 1977. I had only been as far west as Utah prior to that time. It was a tremendous adventure for me. I remember getting in my old, beat-up jalopy car and driving it 2,000 miles mostly across arid lands and then arriving at-

SS: Praying that it made it, right?

RI: Yeah, praying that it made it. I had plenty of water along just in case. Then crossing into California, crossing the Sierras, coming down into the Bay Area and everything I felt like I was entering a sort of fairytale world because I had heard about this place all my life, but I'd never seen it before. That was a big deal. Then that very first summer that I spent on the west coast I'd made 00:13:00a trip up to the Pacific Northwest. My parents and my younger brother had come out on a camping trip, had traveled all the way to California and then collectively as a group we came up to the northwest. That was my first exposure to the volcanos of the northwest. Prior to that time, I had never seen a volcano. Of course, we passed by a lot of them. My brother and I even made kind of a half-hearted attempt to climb Mt. Rainier at that time. We were under-equipped.

SS: That's not an easy mountain to climb.

RI: I climbed it later in my more-informed and more-equipped years. At that time, we were poorly informed, poorly equipped and so it's probably a good thing that we turned around where we did.

SS: How far did you make it?

RI: We made it up to a place called Steamboat Prow.

SS: That's about 11,000 isn't it?

RI: About 10,000.

SS: 10,000?

RI: About 10,000 feet, yeah. It's really where one of the two primary climbing routes on Mt. Rainier is, but it's really kind of the halfway point in terms of 00:14:00getting to the top. Anyway, but it was spectacular because I had always imagined really liking and appreciating the Pacific Northwest just based on what I'd read and seen on television and so forth.

SS: I'm going to return to that in just a minute. I want to get your impressions of the stratovolcanoes, the topography and the geomorphology here, but you did mention Utah. For a geologist and especially in terms of geomorphology, that's a paradise.

RI: Oh yeah.

SS: A photographer's paradise for me. I wrote on Canyonland. What was the impression you had when you first saw Utah stuff?

RI: At that time, it was just a very brief and short foray into northern Utah, into the Wasatch County and so no exposure to the spectacular Canyonlands country.

SS: Okay, you didn't see that. Okay.

RI: I didn't see that until many years later.

SS: Oh, okay. Then I'll retreat on that question. I thought maybe you went there 00:15:00and you were just so inspired you became a geologist.

RI: It was really more, the single place that inspired me the most was the Tetons.

SS: You mentioned that early on.

RI: That spectacular mountain front which is really unlike any other in the United States in the sense that there's of course this very flat valley floor of Jackson Hole and essentially no foothills between that and the mountain front and so it's very impressive and seeing that for the first time really left an imprint on me.

SS: When you were in high school did you have an affinity for science or geology, or did that develop when you got into higher education?

RI: I certainly had an affinity for science, and particularly for math when I was in elementary school student right through high school. I took as much science and math as I could. I was interested in other subjects as well, but it always seemed to me that I probably would want to pursue a career where I could 00:16:00take advantage of my interest in mathematics.

SS: But you didn't really know about geology or whatever until you got into college, correct?

RI: Well, I took an Earth Science class when I was in high school, but frankly it was, for lack of a better term, it was a little bit lame. We didn't really learn very much, and it wasn't well-connected to other sciences. I think part of what makes geology interesting is the way it connects with other sciences and that was omitted from that high school class.

SS: One of the coolest things for me was when I got into my doctoral studies and I studied under Stephen Pyne and got into all the stuff, the way he approaches everything and basically everything we did it was contextualized by geology and biology and you would study how Charles Lyell affected Charles Darwin and how Humboldt's holism transferred into this and all of a sudden to me geology for a 00:17:00historian it's like a sister discipline for me.

RI: Well, it's interesting you should mention Stephen Pyne because I think I'm correct that he's the one who wrote the book, G.K. Gilbert A Great Engine of Research, and I think that was based on his Ph.D. work.

SS: Yes, that was.

RI: And G.K. Gilbert is more than anyone else the early geologist who I've always held in high esteem.

SS: Because he was into mechanics.

RI: He was into mechanics. He didn't do it mathematically, but he had a very clear conceptual understanding of mechanics. I've always been a great admirer of G.K. Gilbert, beginning when I was in graduate school when I first started learning about his work.

SS: That was one of my questions. What a surprise huh? No, but I mean in studying the Colorado Plateau and you look at Powell's survey and Clarence Dutton wrote all of the artistic, did all the stuff, and Holmes wrote those incredible sketches of the Grand Canyon, but Gilbert was the mechanic guy. It 00:18:00was kind of a balance between, and Powell's kind of a synthesizer and government operative.

RI: Exactly, and the same would be true of Clarence King. These guys were all very big-picture guys, whereas Gilbert more than anyone else at that time was attentive to detail and thinking about the mechanisms by how things actually worked.

SS: I suppose you've read his analysis of the Henry Mountains?

RI: Oh yeah.

SS: I've climbed them, and I took it up there and I read it on top of Mt. Ellen.

RI: Really? I've driven by the Henry Mountains, but I've never actually been up into the Henrys.

SS: They're very isolated.

RI: Oh yeah.

SS: It's not something that tourists go to. They drive to the parks around there, but it's funny it's the last mountain range to be named by the U.S.

RI: Yeah, well it's so remote and it's small and it's isolated and yeah.

SS: Very interesting. Iowa State, what did you study? Did you start in geology or did you kind of develop into that?

RI: I really didn't know what I wanted to major in when I entered college and very quickly, and as I recall this was during my freshman year, I realized I was sort of at a bifurcation point because I had this very strong interest in science and mathematics, but at the same time I thought that I wanted to be a writer because I've always been interested in writing and just beyond writing scientific papers, I mean other kinds of writing: essays and even a novel and that sort of thing. A definitive moment for me was during my freshman year I didn't have a car and I was catching a ride from Ames back to Sioux City where my parents lived with a guy who was a professor of journalism at the university who was a friend of my dad's. We had 3 hours of time trapped in the car together to talk.

He was asking me about what I was going to pursue as a career and a major and so 00:20:00forth. I explained to him that I was struggling between do I choose science, or do I choose writing and be an English major or journalism major or something of that sort. He counseled me. He said, if you have an interest and ability in science, I strongly encourage you to go into science. He said the reason is the following, and he was absolutely right: he said if you don't pursue this science education now, you'll never be able to catch up with it later, because this is something you have to start learning systematically now. It's hard to be an amateur scientist nowadays.

SS: Back in the days of Powell, he only had a master's degree. And he was basically trained in the field.

RI: Sure, yeah, a lot of them were.

SS: But you could never even get a job at a university today with that.

RI: A lot of them were semi-self-trained in those days. He said on the other hand with writing this is something you could always pursue at a later time, if 00:21:00you choose to. It's actually something I'm hoping to do in retirement it to spend more time writing other than just my scientific writing. I think he was absolutely right. It was some of the best advice I've ever received. Basically, I made my decision shortly thereafter. I'm going to follow the science track and then really what, I was sort of debating between geology and physics is what I wanted to specialize in. What really sold me was simply the fact that the geology labs were so much fun. We would either spend our time going through maps and looking at rocks and specimens and fossils or whatever it might be. But more importantly we would go on field trips and visit streams where we could see things actually happening in real time. It was so enjoyable to have that very tangible connection to nature, whereas of course physics is very much about nature but it's very much at an abstract level. It's not that sort of tangible this is what we see every day in front of us, other than at the most basic level 00:22:00of the cup falls on the ground if I knock it off the table here.

SS: You have models and more models.

RI: Yeah.

SS: Versus models and nature.

RI: Exactly.

SS: Is that a good, crude analogy there?

RI: I think that's a reasonable analogy. I ended up having as an undergraduate my major was in geology. I ended up getting minors in both math and physics. I continued to pursue those things.

SS: That's exactly what happened with your career, am I correct?

RI: That's exactly what happened with my career.

SS: Because I mean just hearing you talk last night and reading some things that you've written, that's kind of who you became in your field.

RI: Exactly.

SS: That's very appropriate. How did the transition happen out of Iowa State into graduate school? Did you get your masters at Iowa State?

RI: No, just my undergraduate degree.

SS: Okay. Then you moved on to Stanford, or was there another school you went to?

RI: No, I moved on to Stanford. The way that I wound up at Stanford. I was frankly not a terribly well-informed student about the nature of graduate 00:23:00education and how the larger world worked. I only applied to a couple of graduate schools. They were both in the west, but they were two very distinctly different places. One was Stanford, the other was the University of Montana. I think my notion was that if I went to Montana, at that time I was already an avid cross-country skier and I probably would've ended up majoring in skiing to some degree.

SS: You would have ended up at Big Mountain or wherever else all the time.

RI: Something like that, yeah.

SS: Or down in-what's the one down by Bozeman? Yeah...

RI: I just wasn't aware I think the way students are nowadays in general I think students are much better informed and maybe more competitive nowadays than they were back then, but I was not acutely aware of the fact that there was a hierarchy of universities. To me, one university was kind of like another.

SS: So, you didn't think that when you got accepted to Stanford, wow, I'm on the 00:24:00farm now?

RI: Yeah, it didn't seem like that big of a deal, but in retrospect I'm very happy that I went to Stanford because I realize that it opened all sorts of doors of opportunity to me that probably wouldn't have been open otherwise, not least of which is that Stanford is located only 2 or 3 miles from the western regional center of the USGS in Menlo Park, and that was what eventually got me established with the USGS. I started working there while it was at graduate school at Stanford.

SS: Going back to Iowa State, but jumping ahead to Stanford, what professors or classes or experiences were particularly impactful and pivotal in your career, and give me some couple names, perhaps.

RI: As an undergraduate, certainly at that time the part of geology that most attracted me was geomorphology. I was interested in what happens where I can see it on the earth's surface and it's happening right now, rather than what happened 100 million years ago. The geomorphologist that I was with at that time 00:25:00was a guy named Robert Palmquist, and I took every class that he taught.

SS: This was at Iowa State?

RI: At Iowa State.

SS: Right.

RI: I took every class that he taught. I also did a couple of independent study projects under him. I did a project mapping cirques, glacial cirques, in the Big Horn Mountains in Wyoming and I did another project that was constructing the elements of a model for rainfall runoff. I was very interested in geomorphology early on and so he was quite influential in that respect in terms of nurturing that interest of mine. Then when I got to Stanford, the people who impacted me most were probably two, no really three, one of whom was my advisor, Bernard Hallet, and he was a glacial geologist himself, but was a very mechanics-oriented glacial geologist and again really nurtured that interest in applying mathematics and mechanics to geologic processes. I also took courses 00:26:00from Arvid Johnson, who was on the faculty at Stanford at that time and who was very mechanics focused. His whole approach to research is that you pursue problems as a problem of mechanics and that really made an imprint on me, even though I felt that I was not very good at it at that time. It took me some years to develop the facility to do the kind of work I ended up doing. The other person who was really important, more from a purely nurturing standpoint, was the chairman of our department, Irwin Remson, who was a hydrogeologist. My first two years in graduate school I was a TA all year long for Irwin's undergraduate classes which were a series of classes called Environmental Earth Sciences. The great thing about Irwin, and this wasn't true just in my case, it was true with nearly all of the graduate students, is the degree to which he inspired our 00:27:00self-confidence and our belief in ourselves. He would give us so much latitude to do our TAing and so forth in the way that we felt was best rather than simply telling us this is what you do, you follow my model.

SS: Which a lot of professors do. A lot of them are a little dictatorial.

RI: Yeah, I can't overstress the importance of the extent to which Irwin inspired confidence in his students. Even though he wasn't my direct line supervisor, to some degree he was a surrogate supervisor.

SS: Dick, just continue along that track please.

RI: Anyway, I was talking about some of the graduate school faculty at Stanford who had a big influence on me, and I named Bernard Hallet, Arvid Johnson, and Irwin Remson who were all in my department which was the Department of Applied 00:28:00Earth Sciences, which is a department--they've morphed their departments at Stanford since that time, so there's no longer a department that has that name attached to it. But the other faculty who most influenced me while I was in graduate school were actually in various departments within the school of engineering. I took lots of engineering classes, both in mechanics and in applied mathematics and that's really where I learned how to apply math to real-world physical problems. As an undergraduate I had this training in mathematics and physics, but again it was at a highly abstract level. It was difficult to relate it to real-world phenomena. It was by taking all those engineering courses that it really helped me develop that facility. Some of those faculty were really terrific. They were just world-class applied 00:29:00mathematicians and excellent teachers as well. There was a fella named Andy Acrivos, who left a big impression on me, and several others. Bob Street was another one.

SS: You told me that you also became exposed to the USGS at that time.

RI: Right.

SS: Because of its proximity but also because of some other reason or a faculty or you met somebody? How did that connection start?

RI: Sure, so my connection with the USGS in any formal sense had an interesting start to it in that while I was in graduate school I took a lot of coursework in all these different departments and that's why I wound up just sort of through happenstance getting two masters degrees on the way to getting my Ph.D., but as I was embarking on my last few years of graduate school towards my Ph.D. I had written a proposal with a professor in the Civil Engineering Department, Joe 00:30:00Franzini, that was going to provide funding for my Ph.D. work. This was in 1980, I guess, that we wrote the proposal. It must have been early 1980, because when Franzini submitted it to NSF he received very encouraging reviews, basically saying we have to go through the formalities of the process, but you can basically expect that this will be funded. That's the word he received.

Well, then, here's where a political connection comes in. Of course, 1980 was the year Ronald Reagan was elected. Shortly after coming into office, Reagan-I'm not sure exactly how this was accomplished, but, in any event, there was a contraction of funding to NSF. There were a lot of program managers at NSF who suddenly found themselves in a position where they had made promises they couldn't keep because they no longer had the funding to keep those promises, and 00:31:00our proposal was one of those that fell by the wayside. Now this leaves me, we're now into 1981 at this point. At this point I'm four years into graduate school, have two master's degrees, and no Ph.D. project. At that point I went to Irwin Remson, our department chair, who had been so helpful over the years, and I asked him for his advice. What do I do at this point? He suggested that I go over and talk to John Bredehoeft at the USGS. John Bredehoeft at that time was the western regional hydrologist, so he was kind of at the apex of the management structure of the old water resources division of the USGS in the western region and he was a very eminent researcher himself, had a long, long track record of very significant accomplishment in groundwater hydrology. I went to Bredehoeft and basically said what can we figure something out here? Is there some way you could fund a Ph.D. project for me? It turned out what Bredehoeft 00:32:00was interested in was using landslides as an analogy for studying earthquake hydrology. He had had a long interest in how distributions of groundwater pressure affect earthquakes. Landslides, of course, are much more accessible. You've got slip going on as you might have along an earthquake fault, but it's much closer to the ground surface and more accessible system to study.

I had all the right background to do this because I'd had lots of hydrology background, I'd had lots of soil mechanics background. But prior to that time, I hadn't really even thought about specializing in landslides. I was really much more interested in fluid flow and sediment transport and sort of those aspects of geomorphology. Bredehoeft said, here's what we'll do. You go off and write a proposal, bring it back to me in a couple of months, and then I'll decide on 00:33:00that basis whether I'm going to fund you. I did that. I worked really hard on this proposal and brought it back to him. It was kind of an informal process, because it was reviewed by a committee of one, that being John Bredehoeft, but when he read it, he was very pleased and so he funded me. At that point, he endowed me with a very exceptional opportunity for a graduate student in that what I had was funding that not only paid me a salary, a half-time USGS salary, but I also had, it was something on the order of $30,000 a year of operating expenses for my research.

SS: So, you had a budget and a salary.

RI: I had a budget and a salary.

SS: You were living the dream for a grad student!

RI: And I also had already, my tuition at Stanford was already all paid off 00:34:00because I had done all these years of assistantships and so forth. I had all that behind me and so now I'm in this position of having a real job.

SS: To write your dissertation, basically.

RI: Yeah. Basically, that was my job: to do the research and write my dissertation. I actually had enough money I was able to pay an assistant to help me. I just paid out of my pocket, paid cash out of my pocket out of this $30,000 I was getting. It just worked great. The other part that was serendipitous about it is that: what the focus of my Ph.D. work was studying a big, slow-moving landslide in northern California in Humboldt County just outside of Redwood National Park. And this is a landslide where-

SS: Where is it specifically, exactly?

RI: Well, it's called Minor Creek Landslide and so it's upstream along Redwood Creek, probably 15-20 miles as the creek flows, inland from the Pacific.

SS: North or south of Arcata?

RI: North of Arcata, but mainly east of Arcata.

SS: Okay.

RI: Anyway, this landslide was a site where the USGS had initiated studies in the early 1970s and that was part of the Forest Geomorphology Project that was initiated by Dick Janda, who was another person who became instrumental in my career because he later was my boss at the Cascades Volcano Observatory. But Dick, along with a couple of other able assistants-Mike Nolan and Debbie Harden-had started this intensive geomorphic monitoring program in the Redwood Creek Drainage Basin and that was something in response to a need at the National Park Service. The situation in Redwood National Park at that time was they had created this park in the 1960s, however much of the watershed had been severely impacted by intensive logging.

SS: They were wanting to expand it [the Park] at that time.

RI: They were thinking about expanding it, exactly.

SS: Correct.

RI: The question was to what degree was this legacy of logging and other kinds of land use impacting the resources both within the existing park and also within that potential expansion boundary? There was no understanding of it. This project was created which became collaborative with the National Park Service to monitor all these sediment sources. One type of sediment source was these big, slow-moving landslides. This was one of several that they had instrumented back in the early 1970s. When I came on board in the 1980s- SS: These were ones where you have the old stake arrays, and you measure how much they move.

RI: Exactly.

SS: Right.

RI: That was the most basic instrumentation: you pound hundreds of stakes into the landslide and survey it with an old-fashioned theodolite and see how fast 00:37:00it's moving and so forth. Then, in addition, have other instrumentation: rain gauges-

SS: Of course, there was slumping and moving [ground] because a lot of the trees and the root structure of the top slope had been lost, or no?

RI: Well, not at Minor Creek and not at many other sites, because these were sites that are actually mainly grasslands with only small copses of trees here and there, which is an interesting ecological question because I know people have puzzled over why should these grasslands exist in a place that gets 2 meters of rain a year in this very mild climate. It's been speculated and to my knowledge it's still speculation rather than fact. It's been speculated that Native Americans actually created these grasslands by intentional burns because they realized that the grasslands were going to provide a greater diversity of habitat and probably improve their hunting opportunities and so forth. But I'm not sure that anybody knows the answer to that. At least I don't know the answer to that.

SS: Well, it's basically what's true up here in the Willamette Valley where 00:38:00everybody in Eugene and other places up here think they understand environmental history that you can't cut any trees down. Well, if you look at pictures back at the early settlement there wasn't a lot of trees around.

RI: No trees, yeah.

SS: It wasn't just because people were clearing them for farms, it's because the Natives had done systematic burning for whatever reasons or just natural fires had been allowed to burn.

RI: Anyway, certainly some of the areas up there that they were monitoring along Redwood Creek were severely impacted by logging and so forth, but not the site that I was studying. In fact, it's one of the reasons I chose that site is that it was in a relatively pristine setting that really its only manipulation by humans was that there was a gravel road that crossed it at one spot. Other than that, it was in a pretty pristine state. It had been monitored to a degree for 10 years and basically what I did in the early 1980s was install a great deal more instrumentation, spent an entire summer there drilling holes, taking 00:39:00samples, installing instrumentation and so forth and then collected a few years of data and that became the empirical part of my Ph.D. work.

SS: That's all yours so...

RI: Alright, yeah. Sure. Anyway, I pursued this Ph.D. project that was two-pronged. Part of it was monitoring this big, slow-moving landslide in Humboldt County and then part of it was developing a theoretical model to try to explain how the landslide moved. That was my first serious attempt at really using relatively sophisticated math and mechanics to try to understand something geologically.

SS: An actual applied, real-life situation?

RI: To apply to a real-life situation and it worked out well. Got my degree and the USGS was sufficiently pleased with it. John Bredehoeft would have been my 00:40:00boss at the USGS and offered me a permanent job at the USGS when I graduated. I would have to go through the formalities of course, but I at the time was really thinking that I wanted to teach.

SS: So, you were kind of like your brother and your sister? You were in that mode of well I'm going to do an academic career?

RI: Exactly. I really thought I was going to pursue an academic career and of course that's the nature of the academic job cycle that good jobs appear somewhat infrequently and in unexpected times and places and so forth. It happened that the year I graduated in 1984 that the most attractive academic job that was available was at the University of Wisconsin in Madison. I applied for that job and I was offered that job. It was really the only job that was of interest to me among the academic jobs.

SS: This was in '83, '84?

RI: This was '84.

SS: '84, okay.

RI: So, I had this tough decision to make: was I going to go to work for the 00:41:00USGS or was I going to go to Madison? Frankly what decided it, again is that it all came back to geography. Although Madison is a wonderful city, if you're going to live in the Midwest, there's probably not too many better places to live than Madison. However, by that time I felt so rooted in the mountain west that it was difficult for me to think about leaving that and going back to the Midwest.

SS: You were spoiled by big topography.

RI: I was spoiled by big topography. And also, the kind of research I did. At that point I've now got quite an investment in studying landslides. Of course, the only landslides they have in Wisconsin are along the bluffs adjacent to Lake Michigan, which is pretty small potatoes compared to around here. Mount St. Helens just a few years previously had produced the world's largest landslide in 00:42:00historic times off the north flank of Mount St. Helens, 2.5 km3. There was all this great geological stuff going on here and much less so in Wisconsin or in the Midwest. I guess at that point I was also aware of the fact that, if I was going to come to work for the USGS, it would be up at the Cascades Volcano Observatory (CVO). The reason was at that time the USGS had a hiring freeze in place, an absolute hiring freeze.

SS: This was the Reagan era.

RI: This was the Reagan era. There was one exemption to that hiring freeze and that was related to Mount St. Helens because Mount St. Helens, people sometimes forget that it had the big eruption in 1980 but then it continued to erupt intermittently until 1986. It was still very much an active volcano. It was perceived to be a significant public threat. So, CVO-focusing on Mount St. Helens--had an exemption for the hiring freeze based on a public safety basis. 00:43:00They said we can hire you but that's where it's going to be. That seemed not so bad. It was sort of a twist of circumstance that led me to wind up at CVO.

SS: In 1980 when the big blow happened, you obviously remembered that. Did you go up shortly thereafter as a curiosity, not even in a formal study way?

RI: No. I didn't. But what I do really regret is that that first trip that I made to the Pacific Northwest, which was in the summer of 1978-

SS: The one you told me about that I wanted to elaborate on further, not, like, right now?

RI: Exactly. On that trip we drove up through northern California and as I recall did not spend a great deal of time in northern California. We were really bound for the Pacific Northwest proper. Spent some time camping in the Three Sisters area, here in Oregon. Continued on past Mt. Hood and I remember being very impressed with Mt. Hood, which is-I remember one view in particular of Mt. 00:44:00Hood from the north side that is very much the view I'm going to have from my property where I plan to move when I retire, outside of Hood River.

SS: I was just going to say in Hood River Valley there somewhere?

RI: Yeah. So, I remember that. And then I also remember that from there we preceded straight to Mt. Rainier and went right past Mount St. Helens. I really wish-

SS: That you'd seen it before, right?

RI: -that I'd had that perspective of visiting and spending some time around Mount St. Helens prior to the eruption, because I still have colleagues who did have that experience. They're mostly older than me and sort of getting on in years at this point, but boy I wish I had their experience. A few of them even climbed the mountain prior to 1980 and I wish I had had that experience because it obviously was a place that was extremely different than the way it is today and very special to people in its beauty and so forth.

SS: Like Jerry Franklin who became very involved with the ecology, he used to go 00:45:00camping around that whole area and he even did some early studies in the area and you kind of have that mythic perfect symmetrical cone, I call it the "Cotopaxi of the North."

RI: Yeah.

SS: You know what I'm saying?

RI: Oh, it was a beautiful mountain. Those views from Spirit Lake, for example, that we now see only in photos and paintings and so forth. I wish I could have experienced that. My first memory of Mount St. Helens was seeing it after the eruption from the air, and this was, I guess it was before I actually started working at CVO, but I had come up to visit as a kind of recruitment trip or something of that nature and I was able to take a helicopter flight around the mountain. But this was in 1984, so four years after the eruption. Frankly, I think any time you experience something from the air and haven't been down on the ground it's difficult to appreciate the real scope of it. It was very 00:46:00impressive flying around and seeing all this stuff from a helicopter and so forth, but it really wasn't until later that I started work there and spent time on the ground that it began to sink into my kind of psyche what a profound event this was and what the scope of it was and the scale involved and so forth.

SS: Just going back-did you travel anywhere else to see some of the other landslides and volcanic eruptions that you mentioned? Like Columbia happened in '82, right?

RI: Well, you're thinking of Nevado del Ruiz.

SS: Yes.

RI: In 1985.

SS: '85! Excuse me.

RI: Yeah. No, I actually did not participate in that Nevado del Ruiz response, although several of my colleagues did. I'm trying to remember-there was a particular reason. There was something going on. That was in the fall of 1985. The eruption occurred in November and the USGS response began right around the 00:47:00first of December. I honestly don't recollect what my conflict was, but given that was early December I would not be surprised if it somehow had to do with the upcoming AGU [American Geophysical Union] meeting. I think what it was I had organized a session, a technical session that was going to take place at this AGU meeting. I felt that I needed to be there. I was supposed to be there to chair this session and I thought well if I go off to Columbia now, I'm not going to get back in time for that and I'm going to be not following up on my commitment here. Retrospectively, it would have been, I certainly would have learned a lot more by going to Columbia than at the AGU meeting.

SS: Have you ever been to that site?

RI: No, I've never been there.

SS: Speaking of something I mentioned after your talk last night, have you ever 00:48:00been to Huascaran?

RI: Never been to Huascaran, either.

SS: I highly recommend it. Number one it's the Cordillera Blanca and from a glaciology perspective and climate change is interesting too. But it's a spiritually impactful experience because the park that's been created where a young guy once was is a giant rose garden about 2 miles long. There's a birthday cake like spiral staircase thing around basically a shrine with a Christ figure on top at the end of it with Yungay right there and so you realize there's 20,000 people below you that were buried and never excavated. I'm just saying it's a powerful experience.

RI: That would be a powerful experience. I would like to visit there and for me it elicits thoughts of analogies with the Oso landslide three and a half years ago in Washington state.

SS: I was going to ask you about that later on about applied geology and preventing human loss of life.

RI: For me I was one of the first-my colleague, Jonathan Godt and I, were the 00:49:00first two geologists on the ground there at the Oso site.

SS: So, we're going to-okay, we're going to-go on about the Oso.

RI: Well what I was going to say is that hearing about the memorial at Yungay, and then there's a similar memorial at the site of the Madison Canyon rock avalanche that occurred just outside of Yellowstone National Park in 1959. The Hebgen Lake earthquake triggered this rockslide and it buried a campground where there were something like 30 people camped who were all entombed and what they did at that site was much like you're describing, albeit on a smaller scale. There's a very tastefully done interpretive center and memorial there to list the names of all the victims and so forth. To me that seems like the right response. In contrast, at Oso, it was a horrific scene. It was really-it impacted me tremendously, emotionally.

SS: And you went out there shortly after, did you?

RI: Yeah.

SS: You were pretty close, right?

RI: I was right in amongst the recovery workers who were slogging through the quicksand and digging out bodies and body parts and everywhere you looked there's evidence of humanity. Some things are just heartbreaking, like a teddy bear sitting over here and a children's shoes over there... just a chaos.

SS: Like when you see a tornadic disaster like John Flynn or something like, the same kind of thing.

RI: What it reminded me of being from the Midwest of course and seeing tornado debris before, what it looked like is that it had been struck by a tornado just blasting everything to smithereens and then you poured quicksand on top of the whole thing to turn it into this kind of nightmarish quagmire.

SS: Because the whole thing liquified, didn't it?

RI: Well, at least the distal part of it was liquified and very fluid and moving very fast and deep, which is why it was so destructive. But what happened at Oso, instead of there being something like a tasteful memorial, there is now a 00:51:00type of memorial there, but it was constructed just kind of by local citizens is my understanding without any real government assistance or oversight. Instead shortly after the event the governor made the proclamation that we're going to recover everybody. We're going to recover everybody out of this deposit.

SS: That's a lot of digging.

RI: Well, 8 million cubic meters of debris.

SS: To dig out everybody?

RI: Well, eventually in a sense. But basically, he made the statement that we will keep searching and we won't let anything else happen there in terms of rebuilding the road and so forth until we've recovered everybody. Well, after several months had gone by, they still hadn't recovered everybody. They recovered almost everybody but there were still a few people missing.

SS: Wasn't it like 60 or 70 or 50?

RI: No, it was 43.

SS: Okay, right.

RI: Which actually made it the most lethal landslide in U.S. history with one exception, and that was an event that occurred in Puerto Rico. Of course, Puerto Rico in some sense is technically part of the United States.

SS: Although the Hurricane Maria victims might differ.

RI: They may not feel that way right now.

SS: But the thing that surprised me about Maria was that there weren't more catastrophic landslides of major loss of human life. Weren't you a little surprised?

RI: Well, there were lots of landslides is my understanding, but the fact that there wasn't an order of magnitude greater loss of life there is astonishing to me.

SS: Cat 5 drilled right through the island. It was amazing to me. I thought there'd be thousands.

RI: Yeah, I thought so too.

SS: I did and I'm grateful. I've got friends and colleague and family friends down there, so yeah very grateful.

RI: Anyway, what was done at Oso was very different. They did a great deal of excavation trying to recover bodies and then there was this whole barrage of 00:53:00lawsuits, which are still not completely resolved. I thought they had been resolved, but my understanding is that now there's a second batch of lawsuits. They're basically trying to pin blame on somebody for this event.

SS: Planners or zoning or what have you, right?

RI: Right-or trying to implicate logging, which in a circumstance like this is simply unknowable as to whether logging could have had any influence. It's more conspicuous when you have shallow, rapid landslides that are actually within the root zone of the soil. This thing was 100 ft thick. It was way, way below the root zone of trees, so who knows. But the whole thing has been, including the science, the whole Oso response has been greatly complicated by the fact that 00:54:00there had been all these ongoing lawsuits.

SS: I'm going to return to this subject and the dynamic in your science and how it applies to human societies, because I anticipate that some of the reason you went into what became your thing was to prevent or at least have better predictive mechanisms.

RI: Absolutely.

SS: Then you have human hubris and forgetfulness and what have you. I will ask you that a little bit later after we get into the debris-flow flume, which is going to be very soon, here.

RI: Sure.

SS: Okay, so now do you think that some of your interest in developing something to study, debris flows, of course the debris-flow flume up at the H.J. Andrews Experimental Forest became your signature thing that you did in that area, do you think that was maybe partly motivated by when you got up to the volcano 00:55:00observatory? You were doing work in the aftermath of the big eruption, there were still small processes going on comparatively, had to do with well I wasn't here for this. I want to develop some way to look at processes in real time because I wasn't here for this.

RI: Well, absolutely. In large part we built a flume simply because it's so difficult to study these things in a natural setting. After arriving at CVO my colleague Rick LaHusen and I had spent a lot of time and effort instrumenting two different sites around Mount St. Helens trying to capture good quality real-time data on debris flows or landslides as they happened, and the short version of that story is that it was a failure. We didn't succeed in either case.

SS: Because nothing really happened, correct?

RI: Well, in the case of one of these sites we had instrumented this channel right at the mouth of the crater of Mount St. Helens, a place called Loowit 00:56:00Channel which had frequent debris flows, but the next one that came down was far bigger than the preceding dozen and just took everything with it, removed all of our instrumentation. All this hard work went for naught.

SS: Of course, in the original debris flow it wouldn't have mattered how big your instrument...

RI: It wouldn't have mattered, yeah.

SS: I mean you go down into that debris flow and you see these chunks. It's stunning really.

RI: Oh yeah.

SS: I know.

RI: So, it's fraught with problems. Any time you're trying to measure something in the field that happens infrequently and where it's difficult to anticipate the magnitude your chances of success are pretty small, really. There has to be a lot of luck on your side to be successful. It became clear to me that the way to study this more efficiently was experimentally rather than through field data acquisition.

SS: Just like going back to the Midwest, another disturbance tornados.

RI: Sure.

SS: They're so unpredictable, even with present-day modeling and satellite imagery. Getting instrumentation in a position to where it can somehow read the inner part of the vortex or whatever without getting you killed.

RI: Yeah.

SS: That stupid movie, Twister. You probably saw it.

RI: Sure. As a consequence, they still don't really understand tornados. It's just so difficult to acquire the data you need.

SS: Anyway, you were talking about Mount St. Helens and you arrived in 1983, three years after the big 1980 eruption, when the studies of geologic and ecologic processes in the post-eruption landscape were in full swing. How did the Mount St. Helens process in its early years affect your professional development as a catalyst for new direction or compelling subject and example of natural processes and disturbance that may have fed an existing interest that 00:58:00was already starting all the different things you studied at Stanford and maybe with your early USGS work?

RI: I would say the biggest influence of my experience at Mount St. Helens had to do with the fact that whereas I had been studying slow-moving landslides, things that move persistently but never more than a few meters a year typically, at Mount St. Helens things routinely happened fast and there were dramatic changes. Of course, the most dramatic of all being May 18, 1980: the huge landslide and eruption and lahars and so forth, but even subsequent to that there were ongoing on a nearly weekly basis in the wintertime significant events: debris flows and so forth happening, tremendous changes happening along the Toutle River in terms of the development of the drainage system and that in turn was influenced by lots of landslides feeding sediment into the river. You could see things unfolding sort of before your eyes at a pace that's sort of 00:59:00atypical geologically in most cases. Keep going? I think for one thing it caused me to refocus my attention more on fast-moving kinds of landslides and debris flows and so forth, rather than these slow-moving ones. Of course, it was also clear that that was really the issue. That was much more significant from the standpoint of hazard assessment and public safety and so on.

SS: Very early on you saw an applied scientific reason for doing what you wanted to do and-

RI: Absolutely.

SS: It had something to do with human society?

RI: Yeah, frankly applications were on my mind from the very beginning, even when I was an undergraduate student studying geology. It was part of the reason 01:00:00that the part of geology that interested me most was that part dealing with the current landscape and current processes and how does movement of water and sediment influence ecology, influence humankind, how, in turn, can humankind change those processes and so forth? That was always very much on my radar screen as something that I wanted to focus on rather than purely abstract scientific questions. It seemed so important to me to try to apply the science as something that was societally relevant. SS: Now, what were some of the central assumptions you may have had, general or specific axioms and paradigms, about debris flows, earth processes in general, about ecological or geologic processes regarding major disturbance events, volcanic eruptions in particular-how were they challenged, supported, or overturned by what you saw at 01:01:00Mount St. Helens, other volcanos, and everything that happened after you got up to Vancouver and after.

RI: I would say, I'm just trying to think if there were any paradigms that were really overturned in my mind as a result of what I saw at Mount St. Helens. Frankly, there's nothing that occurs to me that's very specific. My understanding is that Mount St. Helens really did overturn a number of paradigms from an ecological perspective-

SS: About regeneration.

RI: About regeneration, because it was certainly the impression that most everyone had that there was a hundred percent annihilation, within certainly the close-end part of the blast zone and even for-

SS: Because the scorch was so hot it just fried every biological thing, right?

RI: Absolutely. I guess I was among those who was really surprised by the speed 01:02:00of the ecological response. Places on the debris avalanche that within several years not only had young trees growing up, but amphibians had moved in, there were these whole communities of plants and animals. That was very obvious if you spent time walking around on the debris avalanche. That was significant. In terms of the geology, I think kind of the overturn of paradigms occurred more during the eruption itself because St. Helens really did open people's eyes in a very significant way to the role that huge landslides can play in sculpting volcanos and influencing the types of eruptions that occur and so forth. There had actually been an analogous event that had occurred at a very remote location: Bezymianny Volcano on the Kamchatka Peninsula of Siberia in the 1950s. 01:03:00There had been a flank collapse that had led to a lateral blast, really a close analogy to Mount. St. Helens. This area was so remote that it was largely unknown to western scientists.

SS: Nobody lives close by.

RI: Nobody lives there and whatever had been published was published in Russian and very few Americans-

SS: Did they have any science people that were close enough to be there when the eruption happened?

RI: To my knowledge, no. Subsequent to that eruption-

SS: Because that's a really remote peninsula.

RI: Subsequent to that eruption the Soviets did establish a volcanology outpost there. It exists to this day that there is a science presence, but I think prior to the eruption there was no science presence.

SS: Is that the big 15,000 ft volcano that's there, or is that a different one?

RI: Well, there's a whole series of volcanoes on the peninsula and I'm not sure how Bezymianny stacks up.

SS: Well, there's one that's really big. It's like 15,700 [ft] or something.

RI: I don't think that's Bezymianny. It's a different one, but those volcanoes in Kamchatka, you know look a lot like say the volcanoes on the Aleutian 01:04:00peninsula in Alaska.

SS: Like Katmai and all that.

RI: Very similar kind of setting.

SS: So, it was mainly about the dynamics of debris flows and landslides that St. Helens educated, challenged, gave a profound example of?

RI: Absolutely.

SS: Okay. Now, you're there in the '80s, the Columbia Volcano happens. How would you contrast and compare St. Helens with Nevado del Ruiz?

RI: The St. Helens eruption and landslide and lahars was a very different kind of event, actually, than what happened at Nevado del Ruiz. At St. Helens, of course, there was this immense landslide, 2.5 km3, that removed the flank of the mountain, triggering this huge, explosive eruption. The big part of the story there was not only the landslide and lahars but also the immense lateral blast 01:05:00that leveled, what was it, 230 km2 or something like that, a huge devastated area. At Ruiz, in contrast, Ruiz is a very large volcano. As I recall, it's about 18,000 ft. high, ice clad. Even though it's near the equator, it has a substantial ice cap on it at that altitude. The eruption at Ruiz was actually kind of a piddling little eruption. The explosive component and so forth, and even though pyroclastic flows were too small to be of much consequence in terms of public safety, but what happened at Ruiz is that these hot flows that issued out of the summit vent-

SS: The lahars, right?

RI: Well, they didn't start out as lahars.

SS: Oh, okay.

RI: They started out as dense, pyroclastic flows. At least this is my recollection and scoured and entrained a great deal of snow and ice. Of course, because they were hot, they were very effective at melting that snow and ice. 01:06:00Ruiz is kind of a broad summit, a broad-capped volcano, shaped kind of reminiscent of Mt. Rainier with that broad summit. There's always activity going on near the summit of entraining snow and ice and so forth. Then these flows kind of drop off the top of the mountain and into a topography of very high relief, very steep canyons and so forth.

SS: It's also tropical, too.

RI: Also, tropical. Wet sediment down there. These things now have transformed into lahars up near the summit, but now they enter these canyons and grow enormously in size by scouring material, causing slope failures and so forth along their path. By the time they reach populated areas some 10s of km downstream, now they're big. That was really what resulted in the devastating lahars. It was a case there of minor eruptive activity causing very devastating lahars. That was a paradigm changer I think for many of us.

SS: How so, exactly?

RI: It made us realize it doesn't take much of an eruption to wreak havoc farther downstream in the right circumstances, and we have some very analogous circumstances here in the Pacific northwest, Mt. Rainier being a good example.

SS: The Nisqually River, right?

RI: The Nisqually drainage, the Puyallup drainage, those two being the key drainages of Mt. Rainier that are most vulnerable to these sorts of things. Mt. Baker to some degree is the same way.

SS: What would be the danger of Mt. Baker? It's so heavily ice-capped, too.

RI: The danger there again would be that a relatively modest eruption could end up producing sizeable lahars through melting and entrainment of snow and ice. There, you don't' have population living so close to the volcano but there are substantial reservoirs. Of course, a big flow entering a reservoir could potentially not only overtop the dam but could actually cause the dam to fail.

SS: Are they earth-flow dams, those?

RI: I believe that the critical dams, I'm not certain, because I've actually never visited those dams, but I think they're concrete dams. Of course, that could be a colossal disaster then downstream in which you have a dam failure.

SS: I'm just thinking of the model that you had in your talk last night about earthflow dams and rivulets becoming bigger.

RI: Yeah, right. Exactly, so that could happen, too. If it's an earthen dam it could be this progressive enlargement of the breach.

SS: Wasn't the one down in California that they had to evacuate all the people out. That was a big earth-fill dam, right? The one Oroville, right?

RI: Yeah. It had sort of a concrete face on it, but it was basically an earth-fill dam.

SS: Right, 700 ft high.

RI: Highest earth-filled dam in the country.

SS: I never realized it was that big.

RI: That was a very scary situation. I thought it was going to get out of control, but we were lucky.

SS: Anyway, you're at Mount St. Helens. Tell me about the events and the 01:09:00processes that led for you to realize that you wanted to do something like this debris flow. I believe that there was one other in the world that existed.

RI: No, there was really no other [debris-flow] flume-man, to this day there's really no other.

SS: Even the one in Japan that you mention in your talk?

RI: That's a different kind of facility. The facility in Japan is very impressive. It's a different kind of facility. It's well-equipped for studying the onset of landslides, but it is not constructed in such a way that allows you to study the downslope runout process.

SS: Because they stop it before it-

RI: They stop it at the foot of the slope and the story is over.

SS: And it's not that high anyway, is it?

RI: No, it's not that high.

SS: It looked like it was about 30 ft high, maybe, 40 ft. high?

RI: Something like that, yeah. That, however, that experience of participating in those large-scale experiments in Japan was a seminal event for me in terms of kind of catalyzing thinking about how we could build our own large-scale 01:10:00experimental facility. I probably wouldn't have conceived of doing that had it not been for that experience in Japan.

SS: So, it gave you a visual model of sorts.

RI: Exactly.

SS: And you said, okay. But then you said we want something bigger that can do more.

RI: Yeah, bigger or different, focusing more on the flow dynamics rather than just the initiation process.

SS: How did that process hatch, ferment, go from idea to conception? Take me through that.

RI: Well, the notion that we should try to do experiments, I guess, became clear to me quite early on as we were trying to make these field measurements of debris flows, and they weren't terribly successful.

SS: The ones like at St. Helens you were talking about.

RI: At Mount St. Helens.

SS: Because you couldn't catch lightening in a bottle, so to speak.

RI: You couldn't catch lightening in a bottle. It seemed like studying them in a controlled environment was going to make sense. It also seemed to me that it 01:11:00needed to be done at quite a large scale, simply because I was already aware at that time through doing simple calculations that there were going to be real scaling problems if you tried to do this at miniature benchtop scale. People had done miniature benchtop experiments with debris flows, and frankly I think that's what led to some of the false preconceptions regarding debris flows that existed in the 1980s in terms of what was really important in controlling their behavior.

SS: Just give me a couple of examples of false assumptions.

RI: Well, the most significant example I think is simply that most people in this country, and probably worldwide as well regarded this Bingham Model, also known as the viscoplastic model, as being the best way to represent the underlying mechanics of how debris flows work. The gist of that model is that the material is assumed to flow much like a liquid with the only difference 01:12:00being that it has a finite yield strength, meaning that it won't start to flow until you put enough of it on a steep-enough slope until it overcomes this yield strength and then it starts to flow. But thereafter it basically behaves much like a viscous liquid. I think that that way of thinking about the problem was biased by the fact that people had done these small-scale experiments, these benchtop scale experiments, because when you mix up a batch of mud and run it at that scale it does behave that way. It really does sort of act like a viscoplastic material and the cohesion of the mud provides the dominant resisting force that regulates the motion of this mass of mud. However, when you go to a much larger scale the mud starts to play a very different role, which is that it helps preserve the high pore fluid pressure that develops within this 01:13:00material. That high pore fluid pressure is what enables the material to flow fast and far.

SS: That's a matter of mass and scale, correct?

RI: It's a matter of scale. That effect becomes increasingly important at increasingly larger scales and it grows in importance faster than the growth in scale. If I double the size of the flow, the importance of that pore fluid effect increases more than twofold by doubling this scale. Based on those kinds of considerations I really felt that the experiments needed to be done on a large scale but really didn't think about it seriously, didn't really think about building a facility until I'd seen that facility in Japan and participated in those experiments and realized what could be done at that scale.

SS: That was in the '80s, correct?

RI: That was in 1987. I spent several months in Japan. That made a big 01:14:00difference. The other thing that you start to appreciate in large scale experiments like that is that there's actually an economy of scale. When you scale up far enough you can start using standard construction equipment as part of your battery of experimental devices. The unit cost goes way down. Because now you're buying things at a marketplace that's sold to a million contractors around the world as opposed to having to fabricate some highly specialized scientific apparatus that costs 100x as much per unit utility because it's so specialized. At our flume we used, we have a backhoe loader that's much like what you'd see out on some construction site.

SS: By the way, you were in Japan. When did Unzen Volcano have a big eruption? Was that in the '80s or in the early '90s?

RI: Unzen-so, well Unzen was in the '90s, but there was another event in Japan. 01:15:00I'm trying to remember what year it was. I think in 1984 there was a volcano called Ontake in Japan that had a minor eruption that was accompanied by a sizeable debris avalanche, sort of like the Mount St. Helens debris avalanche, although Ontake is a smaller volcano with a smaller debris avalanche. But it provided one more piece of important evidence about how significant these kinds of events can be at volcanos, even when the eruptive activity itself is relatively modest.

SS: What kind of lessons or even frustrations did your experience, and your colleagues, up at the volcano observatory in trying to historically reconstruct processes from the photos, the videos, measurements in the field? I've seen a lot of that stuff that's been done. What did you learn positively but also, 01:16:00like, this just doesn't take us far enough?

RI: That's a good question. It is true that at St. Helens the eruption of May 18, 1980 was fortuitous in many ways. It occurred at 8:30 a.m. on a Sunday morning. It was a clear, spring morning. As we all know here in the northwest, clear mornings in May are not to be taken for granted. I'm sure they're a minority. The fact that it was a weekend-there were all sorts of amateur photographers and what not distributed around the mountain, had their cameras set up because it was a time of day when they were already out for the day. They were just kind of beginning to putter around their campsite but they had their cameras set up. So, we have this remarkable photographic record of what happened, which is really even today quite extraordinary.

SS: You read Richard Waitt's book.

RI: Oh yeah.

SS: That's pretty cool.

RI: It's a good account of all that. Despite all that, despite this remarkable 01:17:00body of evidence and despite the fact that all kinds of detailed scientific measurements had been made prior to the eruption-

SS: Because there were sensors all over the volcano, right?

RI: Yeah, well to the degree that that was possible. Back in 1980 it was a different world then, in terms of the world of sensors and computers and so forth. But despite all that there were all these unanswered questions about the dynamics of the landslide and what allowed it to move so fast and so far, and so forth, and how did the lahars really get started? What was it about the landslide that allowed it to partly transform into lahars that traveled all the way to the Columbia River and that sort of thing? The great body of evidence answered lots of questions, but it probably posed as many new questions as it answered.

SS: Because there just wasn't enough ways to calibrate and-?

RI: Exactly.

SS: Fred told me about how the Rosenfeld [Gary Rosenquist] photographs they were trying to do time-lapse and estimation of distance and trigonometry and this and that.

RI: That's the thing, the photographs, commonly when you see the photographs of the beginnings of the eruption, they have these timestamps applied. But the fact is none of those were actually timestamped photos. Those timestamps were all applied after the fact through reconstructions and trying to piece the evidence together.

SS: So, there was a lot of room for error?

RI: There was a lot of room for error.

SS: Anyway, you're in the late '80s and you're thinking about doing this. How did the process really begin of I want to do this, here's a design model? How did culminate around in your head and what other collaborators did you have with you that were helping you conceive this?

RI: The way the process unfolded, it really began in earnest when my colleague, Rick LaHusen, and I returned from this experience in Japan because he was with me during that period of several months working on those experiments.

SS: He was up at the volcano observatory?

RI: He's retired now, but yes, we were colleagues for many years at CVO. He was an instrumentation specialist. In fact, I had recruited him to come to work for the Survey for that particular reason. He was so good at doing his instrumentation work. It was after we came back from Japan, frankly probably while we were in Japan, we started talking about what we need is something kind of like this. We need a big experimental facility where we can make debris flows and then study their dynamics as they run out down slope and pick up high speeds and so forth. Arriving back at CVO, soon thereafter, we started to start a campaign of lobbying our managers in the USGS. First of all, just locally, my immediate boss, John Costa, who was receptive to the idea, and then he in turn floated the idea with higher levels of management in the USGS. They were pretty 01:20:00receptive, although there was a tug of war of sorts. There were people who were very strongly opposed to investing this kind of money.

SS: Which was a quarter million dollars.

RI: A quarter million dollars, which was more in those days than it is today. In doing so, on something that was completely different than what had ever been tried before and in trusting a couple of early 30-somethings, meaning Rick and me, with this amount of money and responsibility to do something well and carry it out. There were those who were quite skeptical. But fortunately, the people who really mattered, my direct boss John Costa, and his direct boss, John Conomos, who was in Menlo Park, California, were both very supportive. The lobbying process began late in 1987 and by '89 or '90, I can't remember exactly 01:21:00what year, we'd sort of been given unofficial authorization to proceed, meaning to start making plans. The process then was first of all coming up with a sort of sketch level design, just Rick and I batting ideas back and forth about this is what we want this thing to look like more or less. Once we had that image in mind of what we wanted it to look like, the next big question was where can we possibly do this?

SS: The original sketches are they quite similar to what actually was finally built?

RI: Yeah. They're primitive sketches, but in terms of the geometry, the size-

SS: The gradient.

RI: The gradient, yeah, it ended up being pretty similar to what we originally had in mind. There were some fortunate circumstances in that as well, which I'll get to in a minute. Once we had this unofficial authorization to proceed, the 01:22:00next big question in our minds was where can we possibly do this, because we knew that there was no way we could actually buy land to do it so pretty much had to be federally administered land somewhere. We talked to a number of different agencies who had land in the area. We talked to Bonneville Power Administration, who has a number of facilities scattered up in the Portland, Vancouver area and in the Columbia Gorge and so forth. One of the people I talked to was Fred Swanson, who was the person I knew best in the Forest Service in the Pacific Northwest.

SS: You'd been around him at St. Helens stuff, right?

RI: Well, and I'd also met him years before, actually, at the H.J. Andrews Forest when we were leading a field trip focusing on landslides, both within the Andrews and the larger compass of the Willamette National Forest.

SS: He was talking about the slow-moving landslides?

RI: Slow and fast. Slow and fast. We visited some big slow-movers and also some sites where there'd been rapid, shallow debris flows. I had known Fred for some 01:23:00years. Also, a key person who I haven't mentioned yet was Dick Janda, who was my original boss at the USGS CVO who was an old friend of Fred's and who had also been one of the people responsible for starting that project down at Redwood Creek Country where I'd done my Ph.D. work. Dick was important to have on board as well, even though he had stepped down from his management job at that point and was no longer my line authority manager. Just talking to people about where we might possibly do this and it was Fred Swanson who suggested the H.J. Andrews, which hadn't really occurred to me because I always thought of it as being more of an ecological, forestry research area and how would they think about having a big flume built there. Fred, in turn, I think floated the idea 01:24:00with Art McKee who was the director of the Andrews Forest at that time and possibly with others in the Forest Service and not long thereafter we all got together at Andrews to look at potential sites and here was this site only 100 yards or so from where the headquarters compound area is at the mouth of Lookout Creek at the Andrews Forest. Art and Fred agreed that this would be a good place to do it. Art didn't see any issues in terms of environmental impact really because it was an area that had been logged recently anyway, and just sort of second growth scrub in there. It didn't appear that it was going to harmfully impact anything. I don't recall that we had to do any sort of formal EIS or anything like that.

SS: The thing that I will send you even if you drop-box or whatever, I didn't have time to give you a whole thing. But I've got scanned all the EA preliminary 01:25:00reports that never went to full EIS, but they had a biological survey, a cultural survey, a sensitive plant survey. Just so you know, there was stuff that happened.

RI: Well, I knew that, and that was all going on within the offices of the Willamette National Forest, so we were extremely fortunate that-

SS: Lynn Burditt, that was the District Ranger.

RI: Well, she was the District Ranger up in the McKenzie Ranger District [Blue River Ranger District at that time; now merged into the McKenzie River Ranger District]. Then there were also folks down at their headquarters office down in Eugene who got involved. This individual John Cissel [liaison between the research and land manager communities]. There was another fella whose name is escaping me. But we got a tremendous amount of assistance from Forest Service staff on this stuff. We in the USGS had no experience doing this because we don't manage land. We don't build structures. We don't have that kind of background.

SS: You were coming into this right at the time where the Andrews was a maturing as an LTER site [Long-Term Ecological Research], and their campus was becoming 01:26:00professionalized and nice.

RI: Absolutely. Yeah.

SS: The "ghetto in the meadow"-

RI: Was disappearing.

SS: Was disappearing. You were coming in about that time.

RI: Absolutely and in fact when the flume was under construction, which was in 1991, as I recall that was the same year that they were building, or maybe they had just completed construction of what is now the headquarters building at the Andrews.

SS: I think that had just been finished in '90 or '91. The plans were in '90 I believe.

RI: And the shop building had been constructed already. It's larger today than it was then. But the building had been constructed and they were just starting to work on the first of what are now the several housing units there. So, the flume was built in 1991. It didn't finish construction until late in the fall, so we didn't actually use it until the spring of '92. We did some of the finish work on the flume ourselves, in terms of we built a small instrument shack there 01:27:00and so forth. But the timing was very fortuitous in terms of changes that were happening at the Andrews being basically coincident in time with when we were building the flume.

SS: So, how did it go from sketch to formal design? I know there were some back and forths and geotechnical suggestions and adjustments. I've had the fortune to read all the documents in the last week.

RI: The transition from sketch to formal design, a crucial part of that process was contracting with an individual professor at Portland State University, Franz Rad, who was a relatively recent addition to the faculty there whose expertise was structural reinforced concrete design, perfect for what we had in mind. I guess I was aware of Franz, or first met him, through another guy who I knew at 01:28:00Portland State University who was in the Mechanical Engineering Department who I had recruited one of his students to do some work for us previously, so I had a bit of a toehold there. Anyway, Franz was interested in pursuing this project. I have no recollection of what we paid him in the way of a consultation fee. He was the one who transformed our drawings into actual construction documents, meaning that he created the blueprints that were used by the contractors, both in the bidding and in the construction process. He developed the actual specs for the concrete, for the steel that was going to go in the concrete and all those sorts of things. He transformed it from basically being an idea to something that looked like construction plans. Then the next step was once we had those in place, and there was a lot of iteration between Franz and me. We would bat things back and forth, which was a fun process and a completely unique 01:29:00one in my experience.

SS: It really was good that you had your engineering background because you really could-

RI: I could talk his language.

SS: You could talk shop.

RI: Yeah, I could talk his language. Interestingly the single biggest point of divergence of opinion was how exactly are we going to operate those big steel gates at the head of the flume. At the top of the flume there are these gates that are 2 m high, 2 m wide, and they retain or have to resist about 20 tons of force against them when you have this wet sediment piled behind them.

SS: So, they have to be really heavy and build-

RI: Really heavy and really stiff and strong and have a very secure latch mechanism. Then you have to be able unlatch them and allow them to open very rapidly. We had lots of discussions about what was going to be the best design for these gates. Ultimately, I ended up deferring to Franz's judgment as to how best to do it. I was in favor of a gate that would pivot on a horizontal hinge 01:30:00so that the gate would flip open in a vertical sense.

That design had many advantages, but it had one really big disadvantage and that's in order to open the gate you were going to need some sort of a hydraulic system that could apply a very large force very quickly to lift up this huge steel gate and flip it open. That was a big disadvantage. The advantage of that type of gate is as it flipped open it enabled complete clearance for the sediment to just discharge from beneath it. There was no gate in the way. Whereas, instead what we have are gates that open sort of saloon door fashion, where the hinges are mounted vertically on each side wall and when you unlatch the gate it flips open like a saloon door. Franz's argument was that from an engineering standpoint this was a much more straightforward, more bomb-proof kind of design. I think he was absolutely right. It has minor disadvantages 01:31:00scientifically because, really two-fold, one is that the gate does not open instantaneously and clear room for the sediment to pass through. It's more of a progressive opening. The other is that then the gate when it does fully open it impacts the side walls of the flume and bounces. Those are disadvantages but I think on balance we've now been running the flume for a quarter of a century, we've had no mechanical problems with the gate.

SS: The doors have never broken.

RI: Doors have never broken.

SS: Have you replaced them?

RI: No. No.

SS: They're the originals, okay.

RI: We've replaced the hydraulic system, but that's actually a pretty inexpensive component. In this case it's a very simple, off the shelf hydraulic system, not some huge, powerful specialty system. Whereas, for example, yesterday I visited the big wave tank facility here at OSU and there they do have a huge hydraulic system that has to do something comparable and has to very quickly move this huge steel plate and create waves at high frequencies. It's 01:32:00immense. That's the kind of hydraulic system we probably would have required if we had a gate of the kind I had in mind.

SS: Which would have been more money than you had.

RI: More money and probably more problematic to keep it functioning.

SS: Long-term maintenance, right.

RI: Exactly. So, I think on balance Franz's design was a good one and so that gave us the blueprint for building the flume and the next big step was actually getting, putting out an announcement and getting contractors to bid on the project.

SS: Of course, nobody'd ever built anything like this.

RI: Nobody'd ever built anything like this. The timing was very fortunate because this would have been happening, I guess in 1990 that this solicitation of bids happened and in 1990 there was an economic downturn and I can't remember exactly what the scope of that was and whether it was more regional or national 01:33:00or whatever, but the bottom line is the contractors were hungry. They were particularly hungry for things like concrete structures because I think the downturn had really affected the road and bridge construction industry. In order to solicit bids, we again worked through the Forest Service because they had experts who worked for the Willamette National Forest in Eugene. This was their job. Their job was designing contracts and orchestrating the bidding process and so forth. They basically did that work for us, again with lots of back and forth, but they did the real heavy lifting and so pretty soon we had this announcement went out where other federal announcements go out and we ended up getting four bids, from four different contractors. This was the next stage that was a real eye-opener for me because the bids ranged from about $220,000 to just 01:34:00over a million dollars. There was almost a factor of 5 difference in the bids. My reaction to this, being naïve about such things, I just thought this was baffling. How could there possibly be a factor of five difference in the bids? Again, fortunately the professional contracting folks at the Willamette Forest, being more experienced and knowledgeable, they explained to me, they said you know this is actually kind of common on these sorts of one-off projects. The reason is-

SS: Because people don't know, yeah.

RI: There reason is there's quite a bit of risk involved. It's a new and different kind of thing. They said, moreover, usually when these federal solicitations come out there will be a certain number of bidders who they're just going to take a flyer at it in the hope that nobody else is going to bid.

SS: And they'll get a high bid.

RI: And they'll get a high bid and make a killing on it, an absolute killing on it. Well, fortunately we had competitive bids and not just this one wild-as I 01:35:00recall there was this bid for $220, there was another one that was maybe $300, another one $400 and then way up to a million dollars.

SS: You go with the low bid?

RI: We did go with the low bid, even though the law did not require us to. Again, the contracting folks explained to me that oftentimes the contractor who makes the lowest bid, as long as you do due diligence and make sure this person is actually qualified can make that lowest bid because they're the most knowledgeable and most experienced in doing similar kinds of work. In fact, this company that was based in Roseburg, a construction company based in Roseburg, what they traditionally did was building a lot of small, concrete dams. When you think of building a small, concrete dam you're working in steep terrain, you have to pour concrete on steep slopes and get it to stay in place and so forth. You're probably going to have to do a lot of slope preparation work. Really a 01:36:00whole skill set for building something like this. They did a great job. They-

SS: What's the name of the company?

RI: Well, I'm trying to remember what the name of the company was. It'll probably-

SS: I could probably find it in the records, but for the sake of this recording if you can remember.

RI: Yeah. Maybe it'll come back to me. It's escaping me at the moment. At any event, the project was so successful as a concrete construction project that actually a year later or something it received this, there's an award for excellence in construction in concrete which is given by the Oregon Concrete Association or something of that nature. Maybe it's broader in scope than Oregon, but anyway so the contractor received an award.

SS: Was it for the flume?

RI: Yeah, for the flume. They received an award for the construction. Franz Rad as the designer received the award and we received the award as being the owner of the project.

SS: It's called a hat trick.

RI: And that plaque, it's a concrete plaque with a nice brass plate on it that still hangs down in our instrument shack at the flume. The award for excellence in concrete. It's held up remarkably well. We've made some modest changes over the years. Frankly, wherever we've made changes and added new concrete hasn't generally held up as well as the original concrete.

SS: Because how it was designed? How it was formed?

RI: How it was spec'd.

SS: And the quality of the concrete itself.

RI: The quality of the concrete itself.

SS: Because that's a big deal. People say it's just concrete. No, concrete's not just concrete.

RI: No. It was a very big deal to get the right mix for this stuff and it was a very, very strong mix and fortunately the weather was favorable when they were pouring it. It was cool, moist weather, which is what concrete likes for curing and so forth. No, it's really, really well-built and wherever we've got concrete chipping away or anything it's where we put in patches for reasons, not for 01:38:00structural reasons, but we decided that we had to put in some new instruments or something, so we'd cut away at the concrete and put a patch in or something like that.

SS: Now at the talk you gave last night you talked about it's 31° [slope], right?

RI: Right.

SS: That was basically, 30° was-

RI: 30° was our target.

SS: Your target but you came to the realization that some kind of average gradient for the stratovolcanoes in the northwest was 31°.

RI: About 30°.

SS: Oh, okay.

RI: Well, no 30° was the target, the design target. It's just that the slope that was available-

SS: Was 31°.

RI: Was closer to 31°, and the thing is one of the major costs in building something like this is simply earth moving and we were going to have to do a lot more earth moving if we leveled it down to 30° than if we kept it at 31°. So, we just went with 31°. We were fine with that.

SS: What was I going to ask you? Now, what difference does it make, if any, that 01:39:00this is in this particular climate? For the behavior of the dynamics of the flows and all the stats?

RI: I would say that there was an upside and a downside to the climate of the Andrews for doing experiments like this. The main thing with the Andrews being that it's wet and that the mean annual rainfall there is something greater than 2 m, and I don't know the exact number. But it basically means-

SS: It's 80 something, I think.

RI: Yeah, 80-some inches.

SS: Because you're on the west gradient of the west slope of the Cascades.

RI: So, it's wet and it's sort of reliably wet for about 8 or 9 months of the year and that effectively limits our experiment season to the months of May through September. We've done them at other times of the year. We've tried doing them as early as March.

SS: Because you need it when it's not wet so you can control-

RI: So, we can control water contents. And equally important, when you're 01:40:00working with a lot of electronics, and we have a great deal of electronics at the flume and many, many wiring connections and so forth, water is not your friend in that environment. You've got to keep your electronic connections dry. We work in the rain. We've done a lot of working in the rain there, but it slows us down. It complicates things. It's a lot easier to work when the weather is nice. In the early years when we were really motivated to maximize our number of experiments we started as early as March and we continued through October and we worked in a lot of pretty miserable weather in March and October so now in more recent years we've limited our window for working there. The wetness has a downside. The upside to the wetness there is that we've always had an ample water supply, because our experiments do use a lot of water. We've got to mix up debris flows, which take a lot of water and then we need a lot of additional water for cleaning up the mess at the end of experiments. We've always been able 01:41:00to just withdraw our water from Lookout Creek, which is only roughly 100 yards away from the flume and it's a big enough creek that our rate of withdrawal, which is only 4 or 5 gallons a minute is kind of inconsequential.

SS: Do you remember when it was christened? When it was finished?

RI: Oh yeah.

SS: Tell me about the finishing. Was there like an anointing or a ceremony?

RI: Well, there wasn't so much a ceremony when it was finished, because like a lot of construction projects it sort of approached finish asymptotically and the final finishing touches were things, we did ourselves in terms of, again, building this instrument shelter and that sort of thing. What was more profound, I guess, was the first experiment, the first attempt to actually use the flume.

SS: Tell me about that.

RI: So, the very first attempt was a foolish one that was probably guaranteed to be a disaster because we hadn't thought things through very carefully, I guess. What we did for our very first experiment, and this again we did this in March. The weather was wet and cold. At that time, we didn't appreciate just how much manpower it was going to take for these experiments. There were just 3 of us working there. It was Rick LaHusen, Tony Bequette, and myself. We went down there and the hopper area at the top of the flume behind the steel gates is capable of holding as much as 20 m3 of sediment. Now, in recent years we've never used that much because it proved to be impractical, but for some reason we had it in our mindset we're not going to skimp on the first experiment. We're going to load it right up to the top. We put in a full 20 m3. We also chose to do use pea gravel because-

SS: Without any mud in it.

RI: No mud in it.

SS: Okay.

RI: Basically, because we thought it'd be simple to clean up because there wouldn't be any mud to make a big mess. It'd just be nice, clean gravel. We sort of had it in our heads, or I had it in my head anyway, that what was going to happen when we opened the gates is that this pea gravel would flow down the flume and basically pile up in a heap at the foot of the flume. What I didn't take into account was the fact that it was early spring, and the pea gravel was wet. It wasn't by any means saturated but it was very moist. And moist gravel has a lot of-

SS: Sticks together.

RI: Sort of stick together. It's all due to the capillary forces, you know the little films of water that are binding the gravel particles together. We're all excited. This is going to be the big, grand opening of the flume. We release the gate and the pea gravel, 20 m3 of pea gravel just sort of drizzles slowly down 01:44:00the flume and leaves the entire bed of the flume from top to bottom coated with pea gravel about 10 cm thick.

SS: So, you had to clean that mess that was-

RI: So, now the question is how the heck are we going to get this pea gravel out of there.

SS: Because it's hard to climb out of that thing, isn't it?

RI: Yeah, really hard, especially when there's pea gravel underfoot. When the flume bed is nice and clean, bare concrete, you can walk up and down it without too much difficulty but not when it's got slippery stuff underfoot. There are only 3 of us there to do the work. So, we spent the rest of that week, we were there for an entire week and we spent 3 or 4 days of that week, the three of us, getting this pea gravel out of the flume. The way we did it, this was just-thank God we were young then, because this was just back breaking work. Getting the gravel down the flume was a non-trivial deal.

SS: Couldn't you just wash it down with water?

RI: Well, at that time we didn't have-later we did have a high-pressure pump where we could blast things with water. We didn't have it at the time. So, it was going to be some sort of manual operation.

SS: You can't just sweep it down, didn't you?

RI: Well, what we ended up doing-we started out just trying to push it down with shovels and stuff and that was way too much work. So, what we ended up doing is Tony on the spot, he had, I can't remember if he had a welder with him or how exactly this was fabricated but somehow-maybe we came back-anyway, he fabricated what was essentially a dredge, like a steel plow that fit inside the flume and was designed in such a way that Rick and I could stand on the back of it to apply our bodyweight to it. What we would do is we had a winch on a big pickup 01:46:00down at the foot of the flume and we would drag that winch cable up to the top, hook it onto this big dredge thing, and then we would just stand on it and Tony would engage the winch and we would ride this thing down trying to dredge the gravel down. After 3 or 4 days we finally got all the gravel down to the foot of the flume.

SS: Were there people from the Andrews there that witnessed the first experiment or was it just you three?

RI: I think it was just us three. I think we realized-

SS: Aren't you glad?

RI: I think we realized, I know that this was kind of a high-risk operation and there was a high chance of failure, so we tried to do it when there was nobody around. Of course, that time of the year there are very few people at the Andrews. It's kind of a skeletal staff during that season, especially in those days, more so than today.

SS: So, this was in 1992.

RI: This was in '92, yeah. So that whole first season of 1992 we were down there, we spent a lot of time at the flume. We were down there pretty much one week a month for the next five or six months, and it was just a gradual learning 01:47:00experience of how to use the flume.

SS: How did you write up the learning curve? Almost like not in the sense that we learned all this great science, but we learned how not to and then eventually how to use the flume.

RI: We never did write up a learning curve like that, in part because by and large people don't have interest in something like that when it's a one-off facility. If this was something that other people were going to be doing somewhere else, then they'd probably have interest in learning about our mistakes.

SS: Well, we want to know what happens if you don't do this.

RI: So, the only people who have had interest, and this has been much, much later, just within the last several years is that the Chinese are now building their own flume. The Chinese did come and visit us, and we spent an entire day with them at the Andrews talking about how to try to do it right. I'm not sure if they'll embrace all of our advice, but we did our best to convey our advice. 01:48:00One of those pieces of advice was you need to be thinking about cleanup. Don't just be thinking about how you're going to do the experiments, think about how you're going to clean up after the experiments and have a plan for how you're going to do that.

SS: And this is when the concrete's relatively smooth, because you added-

RI: Yeah, the bumps later.

SS: Texture and bumps, yeah.

RI: Yeah.

SS: And that would have made it harder, right?

RI: Oh yeah, much harder. Thank goodness it was smooth in those days.

SS: Did you ever ski the flume, Dick?

RI: No. It looks kind of like a giant ski jump, but you'd have to be, well, maybe there are crazy young people out there who'd be willing to ski it, but I wouldn't, not with concrete walls on either side. No opportunity to make turns on that flume.

SS: No.

RI: So, yeah, that whole first season was just a learning experience with really no meaningful scientific results. It was all just about how to try to use the facility. The biggest challenge we ran into, once we understood the limitations 01:49:00of what kind and volume of sediment we could use, the next big challenge we ran into was how to seal the gate in such a way that we could retain water behind it and have very little leakage.

SS: As your saturating whatever-

RI: As we're saturating the sediment. Yet at the same time have the gate be completely unencumbered when it opens. We tried a number of things, but, basically, I recall four different attempts, the final one of which was successful. One attempt was just using neoprene flaps. We somehow had the notion that if you had nice, flexible neoprene that the sheer force of the sediment up against it would create some sort of a sealing bond. Then we tried using clay, modeling clay, packing the cracks with modeling clay. That didn't work.

Then we tried various kinds of caulks and so forth that you might use for 01:50:00caulking household flashing and so forth. That didn't work. The thing that we finally tried, which we've been using ever since, and this stuff was quite new on the market at this time, is polyurethane expansive foam insulation. This is this really sticky stuff-

SS: Kind of like the stuff you spray on the roofs in the southwest kind of stuff?

RI: I don't know if they use it on the roofs in the southwest, but they use it for construction around here. If you have just a little gap in a wall, like you've done some new construction, you put in a new electrical outlet or something and you now have a gap around it and you want to fill you buy this spray foam stuff and [whooshing noise] just blast it in there with the spray foam. The thing is the stuff is super sticky and it expands to fill space. That's important but it's single most important property probably from our standpoint is that it for the first several hours after you apply it, it remains 01:51:00really quite pliable. Eventually it becomes almost rigid, but from our standpoint-

SS: But it'll hold long enough.

RI: But, it'll hold long enough. The key for us, and this was a learning process as well, is you apply the foam to all the cracks that you're trying to seal and then you give it roughly one hour of cure time. It's developed a nice, leathery, tough skin on it but it's still kind of pliable. Then you load the sediment in water behind the gate while that stuff is still kind of pliable and the reason you want it to be pliable is that with that 20 tons of force against that steel gate, it actually does flex a little bit. So, the crack that you're trying to seal is not a completely static crack. It's one that grows a little bit through this flexure of the gate.

SS: But that keeps the moisture behind.

RI: It traps the water and the foam is pliable enough that it will kind of expand as the crack expands. And the stuff works, when you do a good job-I mean, like any job you can do a good job of it, you can do a poor job of it, but when 01:52:00you do a good job it's essentially an ideal seal. It works really well, and we learned that totally by trial and error.

SS: It took you a couple of years to figure that out.

RI: Yeah, probably a couple of years before we really had that wired. There was a long learning curve.

SS: Now, describing the learning curve regarding the matrixes and the combinations of materials, explain a little bit about that-from the pea gravel to mud, to water, I mean all the different things that you used.

RI: We realized early on that pea gravel was a pretty poor representation of a debris flow. We never thought it would be a good representation, but it was nice, easy material to work with. So, the first material that we worked with that more resembled debris flow was simple, standard, what the local sand and gravel retailer would just in those days would refer to as their concrete mix. It was just about a 50/50 mix of sand and gravel. The gravel is rounded river rock, sort of ¾" rounded river rock, just like they'd make sidewalks out of. 01:53:00That actually works pretty well. There's enough sand in it and enough fine sand in it that it will actually retain water and retain pore pressure when it's released and deformed. But it's not as realistic as when you add mud to that material. As years went by, we moved more towards material that started with that same sand/gravel mix but to that mix we added 20% loam by dry weight. The loam itself had a grain size distribution such that we ended up with a silt and clay content that was about 8% by dry weight, which makes a nice muddy mixture that we could still work with pretty practically. We've tried using still more mud. We've tried using as much as 50% mud, and then you run into all sorts of practical problems with just getting the stuff wet. Anything that's really muddy 01:54:00just becomes a nightmare to work with, both in terms of getting it wet and then in terms of cleaning it up once it is wet. It just sticks to everything.

The majority of our experiments have been done with one of those two mixes: the sand-gravel or the sand-gravel-mud. We have used other materials. For example, we've left out the gravel entirely and just used a sandy mix, or we've added larger rocks, sort of fist-sized rocks, because big rocks do play an important role in debris flow, so we've done that as well. But the basic materials have been those two mixtures. Then, the other key variable that we changed over the course of the year was just the texture of the flume bed itself. It started out for the first 8 years it was a relatively smooth concrete surface, a broomed finish, similar to what they'd apply to standard sidewalks. Then in the year 2000 we added bumps to the entire, or nearly the entire bed of the flume. We 01:55:00specially fabricated some concrete tiles that had exactly the texture we wanted to produce the amount of friction that we wanted and then laboriously applied those tiles, grouted them to the bed of the flume. That was a project we did ourselves. We didn't hire a contractor. A group of about 8 of us spent an entire week at the flume with this elaborate, orchestrated process of mixing grout and tiling the entire bed of the flume.

SS: Did this work out well?

RI: It did. It's worked out extremely well.

SS: It hasn't broken, or you haven't had to-

RI: It hasn't broken and we, I remember, Matt Logan, who was the mastermind for how exactly we were going to build these tiles and apply them and so forth he used to jokingly he'd say, well, the design life of this, this is about 5 years. He wasn't going to give it more than 5 years.

SS: He wasn't optimistic about the long duration, right?

RI: No, but Matt has a history of building things extremely well and 01:56:00thoughtfully, and the fact is now 17 years have passed and those tiles are hanging in there just great.

SS: Basically, they went in in 2000, then?

RI: The year 2000, yeah.

SS: Okay. What about the sensors? You talked about last night at your talk that that would be really hard to add more. You never have, correct?

RI: We have actually in one location. We have put in a new cross section down near the foot of the flume.

SS: How many were in the original design?

RI: In the original design, what there were, were 3 pods of sensor ports in the bed of the flume and each one of those pods had 6 individual ports. A port consists of a block out in the bed of the flume where there's roughly a cubic foot of concrete that's missing from the bed and there's a hollow underneath that and the idea is you put your instrument in that hollow and cap it off with a metal plate. There were 18 of those in the bed of the flume initially and 01:57:00then, well, I guess initially that's all there were, were just those 18. Then as we added to the runout area at the foot of the flume, we successfully added more concrete to create a progressively larger concrete runout area to contain our flows entirely within the concrete. We added some instrumentation ports out there and then at the time it was coincident with the time that we tiled the bed of the flume we realized that we also had an opportunity then to maybe put in a new cross section of these ports down near the foot of the flume at the 80 m mark. 80 m downslope from the gate.

SS: It's 95 m, right?

RI: It's 95 m top to bottom. We did that and that was laborious because that involved actually sawing into this thick concrete and cutting through a lot of rebar and so forth and then having to drill laterally through the subsurface 01:58:00because these boxes that house the instruments have to have their wires come out beneath the flume along the side of the flume, so you had to drill in laterally in order to accomplish that as well.

SS: Were you afraid that you might compromise the structure by doing too much of that?

RI: No, simply because by that time enough years had passed that we had a great deal of faith in the structural integrity of the thing. Remarkably being built on a 31° slope, there's never been any sign that the structure as a whole has shifted over time.

SS: In terms of land settling or anything?

RI: Yeah, exactly. I think part of the reason for that-well, it's all about the way it was constructed. Part of the construction is that on either side of the flume sort of stepping up along its length are big concrete pads that are bolted into the flume itself and those concrete pads in turn have big rock bolts, steel 01:59:00bolts that are probably 4" diameter or something, rock bolts that go all the way down to bedrock at those locations. In principle the whole structure is pinned to bedrock. What passes for bedrock around there-we're not talking Sierra Nevada granite. It's pretty punky, old semi-metamorphosed volcanic rock.

SS: That's a pretty old part of the Cascades.

RI: Yeah, it's old Cascades and so none of the rock there is very solid. Nonetheless, I think just having anchors that go down 40' or 50' makes a difference in terms of holding the thing in place.

SS: Alright, of course. What about photographic-how was that set up originally and what have you added in terms of? I mean you hear the cameras when they're shooting, I mean there must be several ports or places for that-

RI: Absolutely. We use lots of cameras to record these things from different angles, different locations. That, like so many other things, the technology has 02:00:00changed so greatly over the course of the quarter century we've been working there. When we first started working there, you have to remember what video cameras looked like in those days. So, we initially had one video camera. It was a VHS, full-sized VSH video camera that you carried around in a big suitcase. It cost something like $3,000 for just a primitive VHS video camera and then we started incrementally adding cameras over the years. Still frames, they changed as well, but we started out with more of a full battery of SLR still-frame cameras with motor drives so we could record sequences of still photos. By the mid '90s, that seems about right in my mind, video technology was already changing. Remember there was an 8 mm format and then something they called 02:01:00high-8 or super-8 mm format video camera and we kind of kept increasing the level of technology. Of course, now everything is digital HD and costs one tenth of what our big old VSH camera cost back then.

SS: I can imagine how much film you must have gone through in the still cameras.

RI: We went through a lot of film on those still cameras.

SS: I mean now you can just get chips and shoot as many as you want.

RI: Absolutely and for much less cost. Because we went through a great deal of 35 mm film. In my office I have a shelf that's probably 10 ft long that's full of nothing full of notebooks full of 35 mm slides and black and white negatives of all those old photos. We have digitized all those, however, so they now all of those many thousands of photos exist in digital form. Of course, the digitized version never looks quite as sharp as the original film version. 02:02:00Anyway, the changes in video technology have really helped us a lot. We can do so much more nowadays with these HD digital videos, because you can get sharp stills out of the videos. In fact, to some degree the videos have almost entirely supplanted using still frame cameras at all because particularly the newer 4K HD video stills look just as good as a regular still camera photo when viewed on a standard computer screen. I'm sure if you expanded the image enough, you'd see a difference.

SS: You shoot everything in big, raw type format things where you can blow them up and really analyze micro?

RI: Certainly, with the still photography we've shot a lot of raw photos, so it gives us more latitude for post-processing and so on. We do a lot of stuff that's sort of photogrammetric in terms of trying to infer 3D shapes of deposits 02:03:00and so forth based on photogrammetry. Our way of deploying cameras has changed a lot over the years, too. You asked about that. Where it's changed the most is at the foot of the flume where we've always known that we wanted to do overhead photography because it's really great to have a vertical view looking down on top of that runout area when the deposits are being formed. That, too, was a real learning curve endeavor. The very first efforts at doing that we tried using a balloon, or a blimp, a small helium blimp.

SS: Like above everything?

RI: Yeah, we put a camera in a box and hoisted up on this little blimp and the problem with that is that any amount of wind whatsoever, if there's even a breath of wind, you've got this big, bulbous blimp up in the air and it's just getting tossed. You can't control the thing. Of course, for photos you really 02:04:00want a fixed frame of reference. You don't want something blowing all over. That was a failure. The blimp was a rapid failure. Then we built a, so we put up a tower kind of like one of those prefab metal radio tower type assemblies that went up about 30 ft. On the end of that put a big boom arm and suspended a camera off that boom arm. That actually worked pretty well but it gave us limited range because you could only reach out as far as the boom reached. When the flows got out beyond that point you lost them from the field of view. Then in later years what we did is assemble a second tower, second sort of prefab steel radio-type tower further out in the runout area and we now have an overhead cable that sort of serves as a gantry or tramway for a traveling cable car that has cameras housed in it, which is a much better way of doing the 02:05:00overhead photography. Of course, the improvements in cameras over the years have made that whole process much simpler as well.

SS: Now, the sensors measure speed and force and what else?

RI: Well, the sensors in the bed of the flume measure normal force on the bed; shear force on the bed; which is something that we've only been able to do in relatively recent years because it's a much trickier thing to measure than normal force; pore fluid pressure on the bed; and then suspended above those sensors we have lasers that measure the evolving thickness of the flow passing overhead. That combination of measurements tells you a great deal about the mechanics of the flow.

SS: When do you feel that you kind of had it down of how this thing operated and 02:06:00how you could best use it?

RI: How the flume operated?

SS: Yeah, I mean when could you say I'm comfortable with this creation and getting the best scientific results out of it.

RI: I think we felt really good about it operationally as early as say 1994, so within a couple of years of beginning operations. I felt like we knew how to make debris flows reliably and we could start actually posing important scientific questions. We started doing experiments involving things like runout processes and flow around a curve and that sort of thing. Things you can actually compare to model predictions systematically and it'll be useful for testing and calibrating models. So, we knew by 1994 that we had a really useful tool on our hands and probably the biggest frustration in those earlier years had more to do with our sensor and data acquisition technology, because it was 02:07:00so much more primitive than it is nowadays. We couldn't collect data as rapidly. All of our data had to be transmitted in analogue form via long cables to a central computer and so we might have electronic sensors that were 100 m away from the computer that was logging the data and the thing is transmitting a small, electronic signal through a long cable is inherently a bad idea, because there's all sorts of opportunities for introducing electronic noise and so on. Well, nowadays what we do is we digitize the data very close to where the sensors are, and the data are transmitted through an ethernet cable. Once everything is digitized, it's now basically free of introducing new electronic noise as it travels down the cable. Of course, the computer is so much faster. It's cheaper. Everything is so much better and easier than it was in those early 02:08:00days. That was a much longer learning curve than learning how to use the flume as a mechanical facility. That learning curve of learning how to take advantage of technology to get the best quality data. Of course, partly it was just a financial matter, too. If we had had unlimited financial reserves back in the 1980s, we could have done what the military does and just throw huge amounts of money at it and probably had a pretty good system. But we were doing everything on the cheap, using just off-the-shelf or stuff we fabricated ourselves.

SS: How many questions do you get from the skeptics for the $250,000 higher up from the USGS and how long before you had good answers?

RI: Well, nowadays we really don't have skeptics. I think everybody realizes-

SS: But, back then?

RI: Well, I don't know. I didn't interact a lot with the skeptics. I knew who they were. I think that frankly by 1997, we had pretty much dammed up most of 02:09:00that skepticism, because that's when our first set of major papers came out. Prior to that we'd had some minor publications and conference proceedings and that sort of thing. But in 1997 we had a wave of major publications that really laid out the basics of how we understood the mechanics of these flows to be working. I think once those papers appeared that kind of shut everybody up, because they realized that this was valuable.

SS: That was about the time when essential assumptions that were had about geological processes, debris flows, this was either challenging or supporting or overturning or providing tangible, believable evidence that said, okay, this is 02:10:00for real. This really does. And we have to rethink or-

RI: Yeah, absolutely. It essentially established a completely new way of thinking about the mechanics of debris flows. The fundamental underlying mechanics, there was nothing new about that. It was still Newton's laws. It was still basic principles of mechanics of two-phased systems. But the fact that we could make measurements that demonstrated that this two-phase aspect of the behavior was really important and was really influencing the overall mechanics and wasn't a minor nuance. It was a central element of how you had to think about these things. That was important.

SS: Taking into account-it kind of happens in all fields-Thomas Kuhn's theory of scientific revolutions and the process of this belief and its supporters, no matter what the evidence is originally pushing back and-

RI: Oh, we've run into that.

SS: Tell me a little about that.

RI: Yeah, I certainly have read enough about the philosophy of science as espoused by people like Thomas Kuhn to understand how it hypothetically works. But I think the reality is different in different fields of science. A lot of it has to do with people's perceptions, which they're more than perceptions. They're realities, I think, as to how important it is for people to embrace a fundamentally new view. A lot of those philosophers of science in the 20th century they always use the development of quantum mechanics as their prototypical case because of course for a period of years, maybe a decade or so, there was a lot of pushback against people who were starting to develop quantum mechanics. But very quickly that pushback disappeared because the evidence 02:12:00became overwhelming that this really did work and it really did not only describe real-world phenomena but that some of these were really useful things that were going to be important technologically.

SS: In the practical world.

RI: Yeah. That dissipated the skepticism pretty quickly. Similarly, with the discovery or really the documentation is maybe a better word of the structure of DNA, people knew. There was a real scientific competition underway at that time to try to uncover that because people already knew this was going to be really important. When the structure was published there wasn't a lot of pushback. Everybody knew right off this is really fundamental. This is important. I think that a lot of these people who study the philosophy of science they tend to focus on those really profound things like that rather than what I would call ordinary science, which is more the kind I do. I think the difference with ordinary science is that the consequences of somebody retaining their older 02:13:00cherished view of something are really not very great. They can continue to publish papers and so forth and they can continue to follow the path they've been following without much in the way of consequences because it's not as though the field has suddenly turned like the turning of the Titanic and everybody's got to head off in this new direction or you're just completely left behind. There's still lots of room for people to keep doing things as they have. That's very true in debris flow science. You'll still find people nowadays, it's a minority, but you'll still find people who treat debris flows as Bingham materials and so forth. They can still publish papers and that sort of thing.

SS: Describe Bingham materials

RI: Bingham materials, again, that's a person's name but it describes, the other descriptive term is a viscoplastic material, and what it is, is a material 02:14:00that's a single-phase, homogeneous continuous material that has two important physical properties. One is that it has viscosity just like a conventional liquid, like water or honey being a more viscous material, but it also has yield strength, meaning that it won't start to flow until you have it on a steep-enough slope or there's a deep-enough pile of it. It's more like ketchup. Ketchup is the classic viscoplastic material that a lot of people are familiar with. You put ketchup on a plate, and it doesn't immediately spread out like a puddle of water would. It sits there because it has this certain amount of strength. If you tip the plate to a steep-enough angle, the ketchup will start to flow. It's a very simple way of thinking about things and it also is attractive to people because it's very easy to work with mathematically.

But as far as I'm concerned, it's just plain wrong. I think the majority of the 02:15:00community has appreciated that at this point. But there also can be a disconnect I think between the research side of things and the people who are doing, say, practical consulting work and who don't have time necessarily to read and appreciate all the latest research findings. It's really been in the consulting community that they've continued to embrace this idea of Bingham models and so forth because they can buy off the shelf software that will do this for them and so on. They don't have to get involved in all this more complicated stuff.

SS: What was the importance beyond infrastructure of having this built at the Andrews? Obviously, you have the support of the water, the infrastructure, the lodging, but what about the fact that the Andrews has become a famous ecosystem 02:16:00science, it's learned, it's a community. It's an experience, a place.

RI: Well, you can think of the importance, I guess, in two different ways. The importance to us as a group working at the Andrews is not only all the ancillary services that are available to us there: the housing, the shop, and so forth. Nowadays we have internet access there and so on. There's all this stuff that we probably wouldn't have access to. There are also the human resources. There are the people right there, the full-time employees at the Andrews site who we've interacted with a lot over the years and have been extremely helpful to us when-

SS: I bet you Terry Cryer helped you a lot.

RI: Terry, I mean, to give you an example of a crisis-

SS: He just retired; you know.

RI: Yeah. To give you an example of a crisis situation we ran into one time, we were right in the middle of an experiment. The whole flume was wired with AC line power as part of the greater Andrews power system. We're right in the 02:17:00middle of an experiment and a construction crew was doing some road work down near Blue River Reservoir somewhere and they accidently cut through the main power line. Just like that all the power goes out to the whole Andrews site. We've got this experiment that's at a crux stage. We're past the point of no return. We have to keep going with this experiment. We've lost all our power, so we go running over to Terry who quickly supplies with a couple of big generators and we plug those into our system and so now we've got line power again. They've rescued us that way. They've rescued us when our phone has gone out. Our phone line has gone out on occasion and we've had to fall back on the Andrews phone. They've helped us in countless ways. Then there's a more subtle but broader kind 02:18:00of impact that the Andrews has had on us, which is that just the countless visitors and researchers who passed through the Andrews, most of whom are biologists of one or the other but it's a great, great variety of scientists and almost all them come to understand that the flume is there because it's so close to where they're lodgings are. Many of them will come and watch an experiment if they happen to be on site at a convenient time. So, it's given an opportunity for us to not only expose them to this type of work but educate them a little bit about the kind of work we do and why we do it and why we think it's important and also how it fits into the bigger picture of ecosystem science.

In these steep, sort of temperate rainforests, really, that we have on the western slope of the Cascades or in the Coast Range of the Pacific Northwest, 02:19:00debris flows are such a pervasive process that they really do have a major imprint on redistributing material and nutrients and so forth in these watersheds. One of the best examples I can think of is the redistribution of woody debris. Something people have come to realize over the last few decades is how important debris jams are in small streams in terms of providing habitat for smolts [young fish], whether it's salmon, whether it's just resident fish, whatever it might be. A steep-mountain stream is a pretty inhospitable environment unless it has sheltered areas within it. A lot of that woody debris that makes its way into these channels is there because debris flow has carried it in.

SS: Exactly. What about more existentially about just the energy, the almost existential, spiritual quality of a high-level learned community being there.

RI: Yeah, it's a great place just to be around people who are studying things that you've never thought about before and you can chat with them and learn something about owls or whatever it might be that they're studying. That's been a lot of fun over the years. I've always been very interested in biology, even though I don't pursue it professionally. It's fun to get chances to learn.

SS: Now, if you were going to, I'm going to merge three questions here: what aspects of debris flows were well-understood in the 1980s when you were conceiving this, what turned out to not be well-understood and taking specific examples going forward, maybe some crystal moments, how has the flume helped build knowledge in that area? Some really important moments for the record tell us why this is important and what we've really learned from this.

RI: I think things that were relatively well-understood in the '80s had to do 02:21:00with conditions under which debris flows initiate, and I don't mean it at a high level of specificity, but everybody knew that there was certain ranges of steep slopes and certain kinds of environments where debris flows were more likely to occur. They knew quite a bit about the sedimentological characteristics of debris flow deposits and where they tended to occur, those kind of broader geological framework topics. What was really poorly understood had to do more with the mechanics of how do these flows actually behave and what-

SS: How they start, what's the saturation buildup, what's the break point, that kind of thing?

RI: Yeah and what controls how far and how fast they move. People had always been fascinated by the fact that debris flows that are chock full of rocks and in many cases logs and so forth and have sediment concentrations up around 60% 02:22:00or 70% commonly can flow almost as fluidly as water. Although on a conceptual level I think people realized that liquefaction was part of that, there were no data whatsoever that really demonstrated that. There were no models, mathematical models, that incorporated that kind of understanding. I think one of the real kind of breakthroughs at the flume, and this happened within the first several years as soon as we start being able to make good debris flows and collect decent data, our early measurements that showed that you really did have these characteristic distributions of pore fluid pressure and debris flows, where you had a coarse grain front that was high-friction and that it was basically being pushed from behind by this liquefied body that had high pore fluid pressures, we made measurements that actually demonstrated that and then 02:23:00in addition kind of showed how you could incorporate that into mathematical models. That was really important.

I think understanding exactly how grain size segregation occurs and how these coarse-grained lateral levees form was really important because the levees play such a role in directing exactly where the flow is going to go and what areas are going to be impacted. From a hazards perspective the levees are very, very important. They're pervasive. When you go out in the woods around here and if you're just kind of walking around on something that looks like an alluvial fan, if you look hard enough, you'll almost invariably find vestiges of the evidence of these linear assemblages of boulders that go through the woods and you may ask yourself why are they there? Why are these boulders lined up-

SS: Some flow, some time, somewhere.

RI: Yeah and they almost look as if they were placed there by humans. No, they were placed there by some debris flow many, many years ago. Now it's all grown up with vegetation and you don't really see that other than the boulders. But they're all over the place here in the northwest and in many other environments. So, that was a real kind of eye-opening set of experiments to understand that better. The experiments we've done involving entrainment of bed material, that still is the least understood part of this process, but we understand it a lot better than we did before doing the experiments. That's one though that there's still work to be done. Yeah, quite a range of things.

SS: What about the human applications in terms of whether through publications or actual examples or sharing and what have you with planning in terms of where you should build, where you shouldn't build, what safety mechanisms need to be here if somebody has built or has a city or what have you?

RI: We're really only now, and by now, I mean within the last 4 or 5 years, reaching a state of fruition with this work where it's really starting to impact ways that people can do practical hazard assessments. The reason for that all has to do with development of this mathematical model, which we call D-Claw, and that model development has been going on hand-in-hand with all the flume experimentation for the last quarter century. But the model has now reached a stage of fruition where we really feel like we can apply it with some confidence as a prognostic tool and put those results in the hands of planners and so forth.

In fact, we're doing a couple of projects right now, one of which relates to big debris flows (lahars) that start as rock avalanches high on Mt. Rainier and transform into debris flows that get down into the major river valleys on the 02:26:00west side, the Nisqually Valley, the Puyallup Valley, and can travel up to 100 km downstream and really impact populated areas and infrastructure and so forth. We're doing that work right now. We're doing some similar types of work but on a somewhat reduced scale related to a hazard that exists in the town of Sisters, Oregon, which is downstream along Whychus Creek, which has its headwaters up at Carver Lake, which is a moraine dam lake on the east side of south Sister Volcano. There's been concern for many years, going back to the 1980s, that that moraine dam could breach up on Carver Lake, most likely it would breach if there were a-

SS: Is that right next to Three Creek Lake, or close?

RI: It's close, yeah.

SS: Okay.

RI: Then there's evidence of past moraine dam breaches at some other locations 02:27:00in the Three Sisters and this is one of the few places where there's still a pretty good-sized lake that's perched at pretty high altitude.

SS: So, that can come down and do significant damage in Sisters?

RI: Yeah, well, there were some calculations, simple model calculations, done back in the 1980s that basically predicted a rather catastrophic flood through the town of Sisters as a result of breaching in this moraine dam. Well, now because of our model, which is much, much more sophisticated than what they had available in the '80s, we can do a much better job with that problem. We've done simulations where we simulate a landslide coming down off south Sister, entering the lake, causing a wave that overtops the moraine dam, you then get a flood/debris flow that travels down that channel, hits the alluvial fan above the town of Sisters and then starts spreading out. What we found with our recent calculations is that the hazard to Sisters is probably quite a bit, the town of Sisters, is quite a bit less than what was predicted in the 1980s, mainly 02:28:00because we can now model the 3-dimensional spreading of this flow, instead of assuming it's all going to go straight through town, which is what they assumed back in the 1980s. It's exciting, certainly exciting to me, to see all this work coming to fruition in a way that allows us to give really useful information to people who are tasked with planning and mitigation and those sorts of things.

SS: I would guess that as the debris flume continues to do its work over time this kind of dynamic will be more useful for practical human applications. You were talking about the Chinese want to build one. How has this served as a model that's actually either other flumes in other countries have been built or in the United States, even? Is this the only one in the U.S., though?

RI: It's the only one in the United States.

SS: Okay. But like in Japan, have they built a bigger one?

RI: No. There's nothing that has superseded this. Well, we've actually had quite 02:29:00a few groups come and visit us at Andrews to tour the flume with the notion that they were going to build their own flume. I think that after they saw what was involved and the scope of the effort and so forth, they were all dissuaded from pursuing that idea, except for the Chinese that now have construction underway of a flume that's going to be larger than ours. It's not-

SS: Of course [laughs].

RI: It's not going to-

SS: Like their dam. The one dam that's the biggest thing in the history of humanity.

RI: Yeah, it's got to be the biggest.

SS: I can't remember the name of it, but it's on the Yellow or the-

RI: On the Yangtze River.

SS: The Yangtze, right.

RI: Yeah, the, is it the Three Gorges Dam? I want to say the Three Gorges.

SS: It makes Grand Coulee look like a-

RI: Yeah. And displacing a million people or something who live upstream.

SS: You can do that in a dictatorship.

RI: Yeah.

SS: No NEPA [National Environmental Policy Act] involved.

RI: No. Same thing with building there-so their solution as they've got this 02:30:00huge flume under construction, their solution for disposing of the sediment when they're done with it is that their flume simply terminates into a river. The idea is they're just going to dump all this sediment into the river and let the river carry it away downstream.

SS: How well do you think that will pass NEPA? Not quite, huh?

RI: Not very well. No.

SS: Tell me a little bit about the community dynamics of working with people on the flume. You talked about your original group of 3 and then, obviously, you came to understand what an ideal size was for different sizes of experiments and the labor necessary to do all the various facets. Talk about that a little bit, but also talk about the community of doing this and how do you learn to work with people and know them and tell me how that's affected your life.

RI: Well, the people aspect of working at the flume is a huge part of the 02:31:00endeavor, because these experiments being of large scale, they necessarily require a crew. It's by no means a one-person endeavor. From the very beginning, my partner was Rick LeHusen, who did the original brainstorming with me for how we're going to do this. Once the flume was built, we gradually started adding people to the mix. The next person to come on board was Tony Bequette, who was kind of a build it, fix it, handyman kind of guy who helped with all kinds of important things. Then, over the course of the next few years, for a while we had sort of a stable five-person crew at the flume, and we did all of our experiments with just those same 5 people, the additional two being Jon Major and Kevin Hadley. Then we realized as we got into increasingly complex experiments that were usually more labor-intensive that we needed even more help. So, many, many people have rotated through at the flume over the years and 02:32:00some of them many times over.

Certain people, Mark Reid comes to mind. Jim Vallance, Roger Denlinger, they are people who've helped with this probably tens of experiments there at the flume, or several tens of experiments. Then there's a still larger group of people who might be there for just one specific set of experiments because they have a particular interest, or they might be a student or a volunteer who is interested in helping but is only available for a relatively short time. Most of the experiments we do nowadays are large enough and complex enough that we typically have a crew of about 10 people. It's quite a dynamic in terms of people engaged in all their individual tasks simultaneously, but then trying to orchestrate the whole thing into, it's like conducting a symphony or something, where you've got to make sure the violins, you sort of entrust the violins to be doing the right 02:33:00thing, but we've got to make sure the violins are in synch with the-

SS: Cellos and the bass and the drums.

RI: The people over here and the cellos and the, yeah exactly. That's usually my job is to be that sort of orchestrator. It's worked remarkably well over the years. Another interesting part of the dynamic, which I think really helps from the standpoint of working together is we all live together while we're there at the Andrews. We're sharing an apartment, and you're cooking and eating with these people and so in the evening you have time to-you can either talk science if you want to or you can just completely unwind and drink your beer and play darts or whatever it is you're going to do.

SS: Sometimes you can even interact with other scientists and grad students who are out in the Salt Salmon [building name] overhang, you know?

RI: Exactly. And the best times are when the weather is really nice in the summertime and most people are outdoors in the evening and that's when you really get a chance to interact and people aren't hunkered down inside their 02:34:00apartments. The people dynamic is really important in any kind of group science endeavor, I think, but probably particularly important in something like this where people have to work collectively towards a common goal but are also doing their individual things and it all has to come together and by and large that's worked out very well. I should mention one other key person who just retired but who worked with us for about 20 years at the flume. His name is Matt Logan. Matt has been my key right-hand man for 20 years and-

SS: He's also up in Vancouver with you?

RI: He's up in Vancouver.

SS: Okay.

RI: He has a skill set that ranges from digital photogrammetry to building stuff. He's a master technician when it comes to fabricating equipment. [He] can 02:35:00weld any kind of material and he's built countless specialized devices for us that exist nowhere else in the world. He's essentially an inventor. He'll take an idea of saying this is what we want to do. We want to contain sediment in the following way. He'll figure out how to build it and make it work.

SS: He's your Leonardo, right?

RI: Yeah. Having somebody like that is incredibly helpful at a facility like the flume.

SS: What were some of the biggest surprises scientifically that have occurred at the flume or disasters or funny events or things that went weird and wrong? Just start out with the surprises scientifically.

RI: Well, I can think of-one of the more interesting, counter-intuitive things we found at the flume is that when we roughened the bed of the flume-so this, again, prior to the year 2000, the bed of the flume was just smooth, broom-finished concrete. Then we surfaced it with these bumps which make the 02:36:00bottom of the flume kind of look like the bottom of an egg carton, that kind of rough, textured surface with sort of similar amplitude bumps. Intuitively you would think that okay you increase the roughness so drastically. Surely the flows won't go as far.

But in fact, what happened after we put in the bumpy bed is that our debris flows actually ran out farther than they did with the smooth bed. The reason for that had to do with the fact that the bumpy bed increased the efficiency of the grain size segregation process, which in turn increased the efficiency of the flow in building these lateral levies that confine it once it starts running out at the foot of the flume. As long as the flow is self-confining, it's able to just kind of keep its longitudinal momentum going and it runs out a farther distance than if it spreads out laterally and so with a smoother bed there would 02:37:00always be more lateral spreading of the deposits, simply because the levee development wasn't as pronounced. So, some really counter-intuitive things like that. In terms of sort of funny or unexpected things, I guess what I think of-

SS: Well, the first thing, number one-

RI: Oh, yeah, yeah, our first-

SS: It wasn't very funny, though, when you were cleaning it out.

RI: Well, I was going to say most of these are the sorts of things that are only funny in retrospect.

SS: Like shoveling the pea gravel out was not funny at the time.

RI: Yeah, moving 20 km3 of moist pea-gravel by hand, yeah, that was not funny at the time, but it is retrospectively. Another event kind of along those same lines, well, a couple of things I can think of. One is that one of our very first experiments, in fact, it could have been the first experiment that we did where we ran a water flood across an erodible sediment bed. So, we've lined the 02:38:00bed of the flume with sediment, discharged 6 km3 of water on top of it, the question is what's going to happen? In the first one of these experiments out in the distal part of our runout pad, we had an individual, Roger's his name, who had a video camera set up out there. His job was to film this flow coming down the flume toward him. I think because he was viewing it through the viewfinder of the video camera and not doing it in person, he didn't fully appreciate how fast it was coming and how rapidly it was approaching him. Anyway, he got overrun by the flow. It's the only time we've ever had that happen; somebody get overrun by a flow.

SS: Was it funny or scary or both?

RI: At the time it was scary. It was scary because it knocked him down. It covered him with mud and debris and so forth. He wasn't injured by the impact, but in the process of this he was wearing glasses and his glasses got broken and 02:39:00he got a piece of glass in his eye, or several pieces of glass in his eye. It was bad enough I took him down to the hospital in Springfield. Luckily, they were able to get the glass out without too much difficulty. But it was pretty scary at the time because his eye, you know, you don't want to have something like that happen to your eyes.

SS: So, this is the only real accident in the history of the flume?

RI: That's the worst accident.

SS: Oh, okay.

RI: There had been a lot of really minor accidents. You know, the-

SS: Slipping on the flume when trying to-

RI: The skinned knee. The smashed thumb or whatever, but nothing that has seemed, well, there was one other incident that was scary that also seemed potentially lethal. In fact, even more so. This was probably 15 years ago, something like that. We were in the process of setting up an experiment. It was 02:40:00just sort of a standard debris flow experiment, where we'd open the gates and let the flow go, no erodible bed. It was getting close to the time to release the flow, so the sediment was charged with water. It was completely saturated. One of the folks who was working there, she later worked on a lot of experiments, but she was a relative neophyte at this time. She climbed into the flume 32 m downslope from the gate in order to make a final adjustment. I think what she was doing was cleaning the, there's a glass protective plate beneath the laser, and it was splattered with mud and she was just going in to clean the mud off, make sure there was a good, clear view for the laser. For very mysterious reasons that we still don't completely understand other than clearly there was a voltage leak somewhere, the gate spontaneously opened. It's the only time it's ever done that. Because the gate has sort of a failsafe mechanism on 02:41:00it, but in this case, the failsafe in the sense that it has to be engaged in two separate places. In this case, the primary initial engagement had already taken place and so it was just waiting for the final trigger. Somehow there was a voltage leak in the system that was enough to very, very slowly power the hydraulic pump that withdraws the latch mechanism. But it was so slow that you couldn't hear it. Normally when that pump grinds you can hear it [grinding noises] grinding away.

SS: Get out of the way! Right?

RI: But this time you couldn't hear it and just all of a sudden, the gates open. So, here's now this debris flow bearing down on this woman who's only 30 m away.

SS: In the flume?

RI: In the flume. She fortunately had been there enough at that time that she knew exactly what was going on and she just deftly hopped over the side wall just before the flow came past and-

SS: That could have really hurt her.

RI: Well, it could have killed her, could have killed her because it would've knocked her down and probably dragged her the length of the flume on bumpy concrete.

SS: And she didn't have a helmet on, did she?

RI: Well, and that wouldn't have helped in that circumstance, anyway.

SS: So, that begs the question how easy is it to get insurance for the work up there?

RI: You know it's a federal facility and the federal government doesn't insure anything. Self-insured as they say, which basically means no insurance. Yeah, so we've hit some scary, scary things like that. Those two are definitely the most scary. There was one other one that was scary, only to me, and it turns out it was just a joke that they played on me. Over the years we've quite a few film crews and stuff most of whom have done, well, they range from those who are quite sophisticated and very focused on creating a good educational film, people 02:43:00from NOVA for example. At the other end people who are there just to have something dramatic that they can flash on the screen and they don't care at all about the science.

SS: Especially in the modern day where everybody's got a YouTube of everything else.

RI: In one of these other kinds of film crew episodes, they had shown up and they brought this-I can't remember this girl's name, but she was a child star. She had her own TV program on cable TV or something where you know it was let's go touring with Susie, or whatever her name was, and we're going to go all around the world and look at all kinds of crazy stuff and she'll tell us about it. So here they are at the debris flow flume and she's acting as the master of ceremonies for the camera and telling them what's going on with the flume. Well, unbeknownst to me, so I'm up working at the top of the flume. Traditionally when we release the flows I'm always at the top of the flume and I'm the one who 02:44:00triggers the release. I'm busy doing stuff up there, not paying much attention to what's going on down there. This film crew thought it would be funny if they brought with them a mannequin and to have this mannequin overrun by the flow. So, I'm up there doing my thing and time comes to release the flow and we release it and I look down the flume and here apparently is this human being standing like-

SS: You didn't know it was a mannequin?

RI: No, and like right in the path of the flow. I just scream bloody murder. I thought it was this little girl, this child star who was just standing there or something. They thought it was a big joke, but at the time it didn't seem very funny.

SS: I bet you were not pleased.

RI: No, I was not pleased. I didn't think it was very funny. They were a real nuisance to have around, anyway, that crew. They were just in our way.

SS: Now, have you been there for every experiment?

RI: I missed one, back I can't remember what year it was.

SS: What did you say on the chart, the graphic of-163?

RI: 163.

SS: 163, right. Over 27 years?

RI: 26 years.

SS: 26 years. About 5 ½ a year, 6 a year about the average?

RI: Per year?

SS: Yeah.

RI: Well, no more like 10 a year.

SS: No, I mean 10 a year, excuse me.

RI: No, no actually if you divide-

SS: No, wait a minute.

RI: That doesn't make sense.

SS: 27 years-no, that's about 6.

RI: Yeah, I guess it has been more like 6 a year.

SS: That's why-

RI: I'm surprised the number is that small.

SS: I did the math in my head last night. I thought was I not thinking straight? So, anyway.

RI: No, no, yeah. You're right. About 6 a year.

SS: Okay. But you only missed 1, huh?

RI: Missed 1. I can't remember what the circumstance was, why I wasn't there. I was at a meeting or something.

SS: Now, how has doing this work and not only the visual and experiential aspects of it, but the science and the modeling and the building on knowledge and going from that-how has that affected how you now go out and see real-life 02:46:00examples during the course of your career as you know almost 30 years of this? Describe that dynamic, the back-and-forth between the model and the flume and real-life stuff.

RI: Well, I have to say that when I go out now and look at real debris flows, whether they're in progress, which that's an opportunity you don't get very often. More often what you see is the aftermath, the deposits and so forth. I really do feel that I have a very complete understanding of what happened. Now, partly that's written up in papers and documented with data and calculations and so forth. But partly it's just a, it's a very sort of visceral level understanding because I've watched so many of these things. I've been a firsthand observer to 160 roughly of these debris flows in different circumstances, whether they're impacting barriers or flowing around corners or running up against slopes and whether they're initiating or whether they're 02:47:00entraining sediment. I've been able to witness this all with my own eyes in real time and there's no substitute for that in terms of giving you a strong, intuitive impression as to what's going on. I think maybe people think that I've got a lot of hubris if I go out to the field and I say I think I know exactly what happened here. But what they don't realize is that-

SS: Because of your long experience looking.

RI: The reason is that I've got a lot of experience looking at this stuff when it's actually happening and not just looking at the deposits.

SS: Have you seen an actual, live, massive volcanic or other event that has happened during your whole time or has it always been in retrospect or through or video or something else?

RI: I've seen small debris flows, plenty of small debris flows. I've never personally witnessed a really big one. I have colleagues who have, who for 02:48:00example were at Pinatubo not long after the eruption, and there were recurrent, big debris flows.

SS: There was lahars that covered the whole area, right?

RI: Right, yeah. But I mean fortunately nowadays video documentation of things tends to be so much, there's so much of it available. It's actually spectacular what you can find nowadays, if you go online and just Google name your hazard, you know? Type in high-speed landslide video. You'll get 50 hits of stuff from Europe and China and wherever it might be. Usually it's not been done by scientists, it's done by people who just accidently happen to be there when it happens, and they've got their handy smartphone with them or whatever and they shoot video of it.

SS: Kind of a, maybe not, well related loosely-but tsunamis.

RI: Yeah.

SS: Watching the 2004 Andaman fault one.

RI: Then Tohoku.

SS: Then Tohoku debris flow of oceanic origin. Tell me a little bit about that.

RI: Well, actually there's a strong synergy I think between understanding how debris flows work and understanding how tsunamis operate once they've made landfall and they're now picking up lots of debris.

SS: That was my point, yeah.

RI: Because the leading edge, that's so striking in the videos, both of Tohoku and from the Sumatra and Andaman tsunami that once they make landfall if there's debris around-if there are trees, if they're cars, whatever happens to be in their path-it will get picked up and it will get shoved along in front of the flow. I really think that the mechanics of tsunamis making landfall like that need to be modeled more like the way we model debris flows and I've talked with tsunamis modelers about that and they basically agree.

I think we have the mathematical architecture in place for doing that, but it hasn't actually been done yet. I'm hoping it is done. I would like to live to see it done, even though that's probably not work that I'll do myself, because I think we have all the pieces in place to do that. Certainly, it's an important phenomenon, right here on the Oregon and Washington coast to say nothing of around the world.

SS: Well, my wife is from Peru. They have tsunamis and earthquakes there and we are slowly putting together our Cascadia subduction zone emergency kit.

RI: Emergency kit, yeah.

SS: It's not finished yet, but-

RI: It's good to be thinking about because-

SS: Well, 1700 it did happen.

RI: And we all-

SS: What was it they figure? It was a 9 about?

RI: Roughly 9 yeah.

SS: There's like debris evidence way up the river channels.

RI: Oh yeah.

SS: I mean, like, 30, 40 miles, right? In some cases?

RI: Well, I think-

SS: Or is that too far?

RI: I think in the Columbia River there's evidence of tsunami backwash. I'm not 02:51:00talking about a huge wave, but there's evidence that the river flow was influenced all the way back to where Bonneville Dam is today, and of course that's where there used to be rapids. That's where the old Cascades Rapids were.

SS: Right.

RI: So, the river felt the effect of that tsunami all the way upstream to the first big rapids.

SS: What is the expected longevity of this debris flow flume and what repairs are typical of a year or every other year?

RI: Really, it's lasted longer, I think, than we ever expected it to. I didn't really expect that it would still be fully functional probably 27 years after we built it, or 26 years after we built it. But the concrete, the basic concrete structure has held up remarkably well. The only things that have needed attention over the years are usually places where we've monkeyed with things and we've put in new concrete patches or something of that sort. I think that as 02:52:00long as it receives a small amount of regular maintenance and, again, the concrete doesn't need much maintenance other than occasional cleaning. But painting the metal parts, keeping the plumbing (there's a lot of plumbing at the flume, a lot of plastic pipe, a lot of pumps and so forth. The plumbing needs to be maintained). But it's all pretty inexpensive stuff, normally. Just kind of like maintaining a house, you just got to kind of chipping away at it over time.

SS: Do you think it will be here in 25 years?

RI: I would like to believe it will be.

SS: Why wouldn't it be?

RI: Why wouldn't it be? As long as people continue to have interest in using it. That's the key thing. Interest and the willingness and dedication to put the effort into it to actually do it.

SS: Now, if you had an unlimited budget and a wish list, what would be your 02:53:00expansion, extension, or improvement on the debris flume if you had a, oh let's build another one somewhere else. Just give me an idealized vision.

RI: Well, at the Andrews, if I had an unlimited budget, what I would change about the existing facility is it would frankly be nice to put-particularly up at the time of the flume-it'd be nice to put a roof over the whole thing so that it was more protected from the weather.

SS: Mainly because of the electronics you're talking about.

RI: Well, electronics and also the whole process of getting the gate sealed and everything and trying to maintain a water balance. Our biggest problems with rain are up at the top of the flume and the work we're trying to do up there. So, if we had a roof over the whole thing that would be great. If I had to build it over again, there'd be a few things I would tweak with regard to the geometry and so on. Currently the flume slopes uniformly throughout almost all of its 02:54:00length at about 31° and then fairly quickly it transitions through a curve, a catenary curve to about 2° slope. I would broaden out that transition so that the change in slope angle is less abrupt and a little bit more like it would be in a natural alluvial fan setting. I would probably change some things about the configuration of the hopper area up at the top of the flume so that it made it easier to use more sediment and get it wet without worrying about the sediment failing prematurely, because that's been a problem. Particularly in the early years it was a problem. I'd change some aspects of the plumbing system. Now, if I really had unlimited money and we're doing it all over again, but this gets into a whole other order of magnitude, it'd be nice to have a variable slope. But, of course, when you're talking about something of this scale and this weight, variable slope becomes a very non-trivial thing. You're now talking 02:55:00about you know something more like building an aircraft carrier or something.

SS: Really big, yeah. How would this react differently, or not, in like for instance a desert climate? Would the difference on drag or anything else be negligible or would it mean you have less worry about rain and weather in terms of your saturation process?

RI: Yeah, I don't think it would change much about the behavior of the flows. It would be a lot more challenging to come by all the water we need to do the experiments. But the actual character of the flows themselves, I don't anticipate they would change much.

SS: What would you say is the most satisfying aspect of having hatched this idea and seeing its successful operation for 30 years almost?

RI: To me the most satisfying thing is the synergy that the flume work has had with the development of the mathematical model. That was really the single, 02:56:00biggest motivation for building the flume was we needed data to better inform development that would improve mathematical models and then to aid in testing that model. Now we actually have that model and it's good enough and complete enough at this point that we're actually using it for practical problems. Our hope is that in the fairly near future it will become widely available. Meaning, we'll have some user-friendly interface for it that will make it accessible to a much wider group of people. Currently it's arcane enough-running the model's sufficiently arcane that we're the only ones who can use it. But we hope to change that.

SS: Now, a couple retrospectives and then-so, how would you view the debris flume's most important contribution to science and society and more philosophically its legacy. If you want to cite a couple papers or chapters in 02:57:00books or what have you-you might want to throw that into that retrospective question, too.

RI: Okay. I would say the most important contribution of the flume scientifically, which in a sense is also its most important societal contribution, is just the way it's provided reproducible, sort of incontrovertible data that has informed development of a new generation of mathematical models, not only our own model but models developed by other people as well. There are a large number of people now around the world who are using the same basic conceptual framework for building their model that really was initially informed by data from our flume. Since that time there have been more supporting data coming from other sources, but our flume was really the first to establish a framework for thinking about the role of evolving pore pressures and 02:58:00grain segregation and so forth. I think that was really important and the fact that those models are used for practical purposes that inform hazard assessments and so on that's where the societal connection comes in. In terms of how that pertains to things we've published over the years; I mean probably the most single important paper that I've ever written was published way back in 1997.

SS: When you told me about the original important thing that came out of this, correct?

RI: Exactly. That was based in considerable part on those first several years of experiments at the flume, where unsurprisingly we were learning things rapidly during those first several years. The pace has maybe slowed down somewhat over time. We're refining things at this point, but I wrote a paper back then that just had the broad title, "The Physics of Debris Flows." In it I tried to lay out all the empirical evidence as well as a theoretical, mathematical structure 02:59:00for how to represent the basic mechanics of debris flows, how do you model them. A lot of people have bought in to that since that time. That paper has been cited about 2,000 times at this point and it's a pretty widely acknowledged way of thinking about the problem at this point, but it was not true at all prior to that. A lot of our successive work has kind of built on that. Certainly, the work on grain size segregation, work on runout processes and so on-it all feeds back into continuing to refine these sort of prognostic tools, the mathematical models and so on.

SS: Now, retrospectively how would you describe the impact of the debris flow 03:00:00flume, its operations, its findings on your research career and life?

RI: Well, I didn't really anticipate at the time we built the flume back in 1991 but it became the central element of my research career in the sense that it guided the modeling work I did. It provided all sorts of evidence that inform my research as well as that of other people. I've sometimes asked myself the question in the absence of the flume if we'd never built it, what would the trajectory of my career have been? It's a non-answerable question. But chances are it would have been very, very different. I could well imagine that I would've continued working on mathematical models, but they wouldn't have been as well-informed. They would've been more speculative and, who knows, it might have branched off in an entirely different direction. So, yeah, it's been very 03:01:00much a central organizing force in terms of guiding my career, which has in turn has been a central part of my whole life trajectory.

SS: I assume that being with the USGS for basically your whole career has been a very satisfying and a good place for you?

RI: Yeah, I'd say it's become increasingly satisfying over the years in the sense that there was certainly a time when I thought I would leave the USGS to take an academic job because I do enjoy teaching and I always wanted to teach. But when our USGS work has become more satisfying as we've increasingly been able to apply it to practical problems and to see our methods used around the world by other people and something I didn't mention earlier in our interview is along the way we developed this relatively simple statistically-based way of 03:02:00forecasting debris flow inundation areas and that gets used all around the world in a lot of third-world countries and so forth where people don't have very many resources and they're really not equipped to run fancy computer simulations and so on. But, the simple statistically based methodology, which was informed by the flume work, is used all over the place. It's gratifying to know that you've been able to have an impact on people you've never met and never will meet.

SS: And maybe some lives have been saved because of that.

RI: Possibly, possibly, yeah.

SS: That's a pretty good legacy, I think.

RI: Yeah.

SS: Anything else that you'd like to add that we didn't cover, Dick, just in the last few minutes we have left here that maybe I didn't mention or maybe that comes to mind?

RI: I don't know. I feel like, no not really. Nothing that's nagging at me that I feel didn't get covered.

SS: This has been a pretty comprehensive interview.

RI: Yeah.

SS: Anyway, I want to thank you for your time.

RI: Yeah, well thank you.

SS: I've enjoyed it very much, both meeting you last night.

RI: I appreciate you doing it.

SS: Anyway.

RI: Will this ultimately be edited-[recording cuts off].